The clock is ticking. Time is running out. After a rare lull on a frenetic day of transfer activity at Sheffield United's Shirecliffe training base, now enveloped by the South Yorkshire night, there is suddenly a chink of light. A deal the club have been working on for two days can be completed.

"Game on?" asks Chris Wilder, the manager, to Carl Shieber, the head of football administration, after he takes an unexpected call from the selling club, who have decided to resurrect the deal.

Shieber raises his eyebrows. He waggles his hand. It will be touch-and-go. They have got 15 minutes until the 11 p.m. deadline. But there is another problem. No one knows where the player is. A call is put into the agent.

"Call us sharpish," says Paul Mitchell, head of recruitment. "There's something to be done. They've come back to us."

This was the denouement to an extraordinary 15-and-a-half hours on deadline day at the Championship club. The day had begun with five players set to sign and two to leave. All Wilder and his team had to do was get the deals over the line.

With unprecedented access, Bleacher Report takes you behind the scenes of everybody's favourite episode of the football soap opera. The fans love it. The managers loathe it. A day when agents hold all the power, transfer fees double at the last minute and players go missing on their way to medicals.

7:30 a.m.

An early start for Wilder. Just as well. Best laid plans have been thrown into chaos. Ched Evans, the striker, may need an ankle operation. And the agreements Wilder thought would be relatively simple to conclude are beginning.

A week earlier, the signings Jerome Sinclair, the Watford forward, and the 19-year-old West Ham United prospect Domingos Quina, were "all but done." But "we've been let down," Wilder says, twiddling his mobile phone through his fingers. "Today is gonna be mad. You won't believe it. It'll be the maddest yet."

For the first time that day, we hear his phone ring. It won't stop until 11:30 p.m. It's a player Wilder knows at another club. He wants to ask him about a centre-half he's interested in. "Is he mobile," Wilder asks. "Can he get up the pitch?"

He ushers us through into the transfer bunker. A small, auditorium-style room where analysts are perched on the top bank feeding data and clips to a cinema screen below. Wilder, assistant manager Alan Knill, Mitchell and first-team coaches discuss the strengths of their targets.

It is difficult to keep up. Punching the initial CD on the board with a marker pen Wilder says, "He'll give us pace in behind." Knill says of another, "He can play all shapes, all combinations." The other initials after Sinclair and Quina are CD, DC and BH. Shieber pops his head around. "Anything you want from me?" "Pizza," laughs Wilder. "And 10 million quid."

8:15 a.m.

In his office, Wilder reclines slightly in his chair and puffs out his cheeks. It's as if he's bracing himself for the twists and turns to come. "It never goes smoothly," he says. "Just wait and see." But so far the portents are good. He gives an update on the deals that are in the pipeline and the names behind the initials.

CD is Clayton Donaldson, a 33-year-old striker from Birmingham City. He has lodged a bid for BH—Ben Heneghan, the Motherwell centre-back. "We think that'll be accepted," he says. They have also been told that Devante Cole, the Fleetwood Town striker and son of former Manchester United man Andy, wants to come. And he might be available for free.

"Sinclair and Quina are almost there," he says. "We've agreed the deal with Watford, and it should have gone through last week, but there was a delay because he needed more time. But he'll be leaving any minute now to come up up here and finalise it. Quina is in Portugal but will have a medical out there and the paperwork is all done."

8:53 a.m.

The first shot of Birmingham City boss Harry Redknapp in his car appears on Sky Sports News.

9:08 a.m.

Mitchell, who has an encyclopaedic knowledge of every player in the professional leagues from watching six games per week, pipes up. He has known Wilder for 25 years. "It looks chaotic," he says. "But all the work has been done on these players."

They have been watched, assessed and analysed to make sure they fit United's criteria for the way they play. "There's a 15-point checklist that looks at technical, tactical and psychological areas," Wilder says. "Few players tick them all, but these boys are all scoring well."

9:47 a.m.

In Wilder's office, Sky Sports News' ticker tells viewers that "Domingos Quina is having a medical at Sheffield United." Looking up from his phone, Wilder says: "They know more than we do."

11:08 a.m.

After a lull, a flurry. Phones are ringing constantly. Heneghan is travelling down for a medical even though the bid for him has not yet been accepted. Wilder takes a call from Redknapp about Donaldson. The deal looks like a goer. "Top, top, top man Harry," Wilder booms. Mitchell says, "I think we might get all these deals done." An air of positivity breezes through the coaching staff office.

Next door, the players are milling around eating breakfast before light training. Three of them, it becomes clear, could be here for the final time. John Brayford has agreed to terminate his contract and move to Burton Albion, more than six clubs have asked about taking winger Nathan Thomas on loan and Scunthorpe United want targetman James Hanson.

11:20 a.m.

Wilder is on the phone to Shieber, who is in another part of the training complex. Details of the Donaldson transfer begin to emerge. It will be a loan with a view to a permanent move. But there will be a loan fee. "These loan fees are new," Wilder says. "I can see why clubs do them, but I don't necessarily agree with them. Could be fifty grand. Could be a hundred with clauses like more money due when we stay up or if we go up."

Wilder talks with Mitchell about selling Hanson to Scunthorpe for £200,000 to fund the Donaldson signing.

11:42 a.m.

Thomas does not want to go on loan. "Fine by me," Wilder says. "But his agent wants to talk with him after training. This is the influence agents have you see. The agent knows one of the clubs has money, so down the line they might try to buy him, and he'll get a cut. The kid is perfectly happy here."

Mitchell lists some of the clubs who are interested. To one of them, Wilder snarls: "He's not going there. He'll be tracking back all day."

12:34 a.m.

Wilder comes off a phone call from Andy Cole, Devante's dad. "He's saying they've told him he can leave on a free, so we're waiting to hear from Fleetwood."

The waiting game continues with Motherwell and Birmingham. "It's hectic, but the whole window is," Shieber says. "We've got a certain amount to spend or use, which was cleared with the board last night on email. I'll spend most of the day agreeing terms with agents before the players get here to speed things up."

1:21 p.m.

With training finished, the coaching staff return. They catch up with the latest and share gossip from around the clubs. "He's got four or five players queuing outside his door," Mitchell says about one Championship boss. Coffees are made and chocolates are passed around.

Wilder, who spent the most recent deadline day getting married, swings around in his chair and suddenly looks worried: "Got a funny feeling about Sinclair, you know? Not heard from the boy's agent to say when he's getting here. What is it, three, four hours' drive from London? A hundred and sixty-nine miles?"

1:50 p.m.

There have been crossed wires over the Donaldson deal. United thought it was a loan. But Wilder is told it could be a straight fee. "Better for us," Wilder says. "He's then our player outright." So how does that work? Does Shieber decide what is a fair price, or is it down to Wilder? "We'll be consulted," he says. "We've pulled out of deals in the past, like for Lee Holmes, who went to Charlton Athletic for £600,000. We thought that was too much."

No sign of Sinclair.

2:34 p.m.

Wilder gets Sinclair on the phone. A frown creases his forehead. "You're still in St Albans?" Wilder gives him a pep talk about the lure of Championship football in front of 27,000 people every week. Later, Shieber tells Wilder on the phone of a story of Sinclair "getting lost, having a puncture" and arriving too late to do a permanent deal to Birmingham so it had to be turned into a loan.

"Same thing's happening again," Wilder says as they spy each other on either side of the car park as they head to the canteen. But it's not the player's fault, he says. He wants to come.

3:24 p.m.

Birmingham have moved the goalposts again for Donaldson. And the signing is in doubt. "This is the madness of it," Wilder says. The deal was agreed for a free transfer with some "small" clauses like a promotion fee. But suddenly, Birmingham have asked for £200,000. "They say another club is interested," he says. "That's fine. We'll sit tight." As for the others Quina is "all but done," Sinclair is due to arrive on the 6:20 p.m. train from St Pancras, Heneghan's arrival is imminent after Motherwell accepted the bid while the Cole still deal hinges on Fleetwood's ability to sign a replacement.

3:33 p.m.

Heneghan arrives. He says he's "buzzing" to sign. At 6'4", he towers above Wilder, who greets him warmly and introduces him to the coaching staff. He goes off to "cross the t's and dot the i's" with his agent, Jake Speight.

3:48 p.m.

The tension is ratcheted up a notch as, unexpectedly, all deals, apart from the one for Heneghan, hang in the balance. Sinclair's agent has called Shieber to say he wants more money. Wilder's brow is furrowed again. "No, no, no," he says. "Can't do that. It's all been agreed with Watford for a week. It's almost 4 p.m.!" Shieber and Wilder speculate as to whether another club is on the hook. Who will blink first?

4:21 p.m.

The Donaldson deal is back on. "It's happening," Wilder says. "Looks like we're paying £50,000." Knill doesn't look up from his phone, opining: "That's a real good one, that. A real good one." Wilder nods. "But we need Devante done."

4:31 p.m.

Donaldson's deal is in the balance again. "It's gone from a loan to 200 grand in total, including clauses," Wilder complains again. "I'm calling Harry—I know he'll sort it."

5 p.m.

Henegan has signed his contract and the numerous registration documents. But there can be no announcement yet, says Kevin Cookson, United's head of communications. "The last thing I do is call my counterpart with Motherwell to agree when we announce it."

It's proof that deals are often all but sealed hours before the fans, desperate for a signing, are told about it.

5:40 p.m.

Sinclair is on the train, but his capture is far from certain. Wilder calls another Championship manager to ask how to deal with an agent suddenly upping the price at the last minute: "It's gone up by 50 per cent!" United's efforts to sign five new players look like yielding just one.

5:49 p.m.

The bad news comes thick and fast. "An agent is telling me we might have to pay £500,000," Wilder says. "He was free this morning." The jovial scenes of the morning are a distant memory. Wilder and his coaches try to second-guess the Sinclair situation. "If it weren't happening, the agent would have told him to get off the train and go back to London."

6 p.m.

"Look at this message from an agent offering these Villa players," Wilder says. "This one must be on £54,000 per week." He goes outside for what looks like an intense conversation with Shieber. When he comes back in, he says glumly: "Sinclair and Quina deals are off." Quina as well? "Yep. Same agent. He says the two are linked so we have to take both or neither of them." What about Cole? "At £500,000 that's definitely off."

6.20 p.m.

Heneghan's paperwork is signed, completing a year-long pursuit. "It really all kicked off last night, though," says his agent. But Motherwell have to sign the same documents as United. And they all have to be scanned. It's a process that takes time. A Sheffield United fan, irked by no transfer activity, tweets "Countdown to meltdown."

7:13 p.m.

Wilder's spidey sense is tingling. "I've got a feeling Devante's gonna come up." Even so, Knill texts Hanson to say he's not going to Scunthorpe. They can't risk losing him. Mitchell calls Devante's agent and suggests he gets in a car to the training ground to save time in case a late deal is possible.

7:25 p.m.

Shieber walks into Wilder's office. A cool customer up until now, he looks disturbed. "I can't believe this," he says. "We are now being told by an agent the fee for Devante has gone up to £1.2 million." Meanwhile, it emerges Sinclair has been sat at Sheffield train station, waiting for his agent to tell him whether he is signing.

8 p.m.

Mitchell is trying to resurrect the Cole signing. He calls Paul Stretford, his agent. The club doctor, who conducts the medical, returns from The Co-op with two chocolate cakes and two lemon drizzle cakes for the final push. Wilder takes a call from the club owners, who want an update on the Sinclair and Quina deals. "Nothing doing," he says. "I don't want the club to do deals that way."

8:35 p.m.

Redknapp has sorted the Donaldson deal, and Birmingham have climbed down from their demands for £200,000. He is on the road with his agent for a medical. Progress is beginning to be made for a late run on Cole, which surprises Shieber:"Normally, if you haven't got a deal in place by 7 p.m., it won't happen because of the time needed to do the paperwork, get the player to the club and do the medical."

9:08 p.m.

Wilder and Shieber are talking about the mechanics of the Cole transfer. They think it could still happen. They are discussing the merits of a £200,000 fee with either an appearances payment to Fleetwood or a 25 per cent sell-on percentage. "They want £200,000 for 50 appearances," Shieber says.

"If he plays 50 times in our team, he will be doing very well for us," Mitchell says. "So that'd be a good deal."

9:23 p.m.

Knill: "When's Donaldson getting here?" Mitchell: "Dunno. But I hope he runs in behind quicker than he drives."

Sinclair, by the way, is just leaving Sheffield train station. He texted Wilder: "Train just getting in now, wish you and the lads all the best for the season ahead." Wilder says he can't help but feel "gutted for the lad. ... He wanted to play, he wanted to come here. So did Quina. That's two lads who wanted to be here but who have been messed about by the system. We'll be walking out in front of 40,000 at Sunderland next week; they'll be walking out in front of 400 at under-23 games. Crazy."

9:39 p.m.

Shieber is constantly on his phone now. He paces the corridors, occasionally breaking off to speak with Wilder, Mitchell or Knill. "Devante is no further forward," he says. But in the parlance of the day, it is "not dead." It could be a loan until January, and Fleetwood appear keen to get it over the line. "I'm getting the paperwork prepared now."

9:55 p.m.

Donaldson appears out of the gloom. Wilder stands in the car park, waving his iPhone with the torchlight switched on. "You still look 19," he says. The pair worked together when Wilder was in charge at Halifax Town 11 years ago. He has tried to sign him four times since. Donaldson immediately disappears into the bowels of the complex for a medical. The doctor will check his eyes, ears, mouth, nose, lungs, heart and abdomen. The physio his joints and muscular and skeletal systems.

10:35 p.m.

With Donaldson in the building and the end in sight, there is some joviality again. Wilder plays pool against the press officer. Wilder jokes that the loser has to run three times around the training field naked. But then Shieber's phone, which had been quiet for its longest spell, rings. It's Gretar Steinsson, Fleetwood's technical director.

"Why are they calling now unless they want to do it?" Wilder says, hopefully to no one in particular.

And the deal is on. Shieber has 25 minutes. Cole will not make it in time for a medical so will sign papers at his agent's office. Chaos reigns as Donna Fletcher, the secretary, runs to and fro with files of papers and contracts. But all the contracts have to be signed and scanned by all three parties. Shieber shrugs, rubs his head and winces.

"I think it's too late." Stretford, Cole's agent, calls Mitchell and asks to speak with him. As he hands over the phone, Mitchell quips: "Ask him for a signed Rooney shirt."

10:45 p.m.

Among the frenzied activity, Donaldson nonchalantly walks back in. Deal done. He is snapped for the ubiquitous deadline day picture, holding up the shirt of his new team.

11 p.m.

Time's up. A pile of papers six or seven inches high stand on Donna's desk. She is on the phone to Fleetwood. The paperwork was received from their end but too late. "The FA won't accept anything after the deadline," she says. "They're very strict. Gotta have a cut off somewhere, and there will be loads of clubs in this position."

11:10 p.m.

Wilder is wrestling with mixed emotions. It has, he says, been a successful day. "Two good players in." And it is the nature of the beast that on such a frenetic day, not all plans can come off.

"Said it would be mad, didn't I," he says. "I knew it would be bad, but not this bad. We've had three boys who were desperate to come and, for whatever reason—completely outside of the control of this football club—they're not here. I was on the phone to Harry Redknapp earlier. He's been a top manager for 25 years, and he says players are the victims on days like this. There's got to be a better way."

Visit Bleacher Report on Saturday for a mini-documentary about Sheffield United's chaotic deadline day.