“Not all blood flows at the same speed, for fuck’s sake!” Geraldine barked, forgetting for a moment that she was on live television.

“Then there was the vomit,” said Coleridge. “Kelly had been drinking heavily, and she rushed to the lavatory in a mighty hurry, didn’t she? But according to what we saw, when she arrived she simply sat down. More curious still, even though the lavatory bowl had clearly been scrubbed clean, the lavatory seat had a few flecks of vomit on it. Vomit which has been confirmed as having emanated from Kelly. How could this be? I asked myself. Watching the tape again I can see that Kelly does not throw up, she merely sits… and yet I know that she was sick. I have vomit from her mouth, I have her vomit from the lavatory seat. Without doubt this is a girl who ran into the lavatory, knelt before it and was sick. Yet when I watch the tape, she just sits down.”

Up in the studio editing box, Pru was having the gig of her life. She had taken over the controls of the edit box and, working live and entirely off-script, she had first managed to ensure perfect camera coverage of the scene unfolding down in the studio, barking cool clear instructions to the shocked team of operators. And now she excelled herself by managing to dial up footage of the murder tape and drop it into the broadcast mix as Coleridge spoke. Once more viewers around the world watched the familiar footage of Kelly entering the toilet and sitting down, this time seeing it in an entirely new and mystifying context.

Down on the studio floor the thrilling confrontation continued.

“Next I come to the matter of the sound on the tapes that were recorded during the murder. In the earlier part of the evening much of what was said inside that grim plastic box was clearly audible, and, I might add, little of it did any of the people you see standing on this stage much credit.”

Coleridge turned to the eight ex-housemates. “Really, you all ought to be ashamed of yourselves. You’re not animals, you know.”

“It wasn’t me!” Layla protested like an anxious school child. “I’d been evicted, I wasn’t there!”

Such was the authority of Coleridge’s performance that, instead of telling him to mind his own business, the other seven housemates, even Gazzer, blushed and stared unhappily at their feet.

“But I’m straying from the point,” Coleridge admitted, “which is that while Kelly remained in the sweatbox we could hear what was being said, but from the moment that Kelly entered the lavatory the sound becomes vague, a mere cacophony of murmuring. Why? Why could we no longer make out any of the voices?”

“Because they were all too pissed, of course, you stupid -” Geraldine bit her lip. She knew he had no proof. She had no need to lose her cool.

“I don’t think so, Ms Hennessy. Seven people do not simultaneously begin to mumble in unison. What had happened? Why had the sound changed? Was it because the sound that I could hear on the tape of the murder was not the sound that was being generated in the sweatbox? Could it be that the person who made that tape did not wish for any discernible voices to be heard from the box during the murder because she did not know who it was who was going to be killed? Strange it would be indeed if the voice of the victim could still be heard in the sweatbox after her death. Was this the reason that the sound on the murder tape was so revealingly anonymous?”

Geraldine remained silent.

“Let us leap forward for a moment in time, to when the note predicting the second murder was discovered. Oh, what a fine sensation that made. But for me, Ms Hennessy, that note was the absolute proof I needed to convince me that the murder was not committed by a housemate.”

“Why, babe?”

Coleridge almost jumped. He had forgotten that Chloe was standing beside him. Throughout his speech she had been attempting, not very subtly, to remain in shot, and she now made a play to really get involved. Chloe felt she had a right, she was the presenter of the show, after all.

“Why, Chloe? Because it was utterly ridiculous, that’s why. Impossible, a transparent piece of theatre. None of the contestants could possibly have known at the end of week one when and how Kelly Simpson would die. Even if they had been planning to kill her it is quite absurd to think that they would have been able to see into the future in such detail and be assured that an opportunity would arise on the twenty-seventh day. So how did that note come to be among the predictions in the envelope? An envelope which we had seen the housemates fill and seal on day eight? Clearly someone from the outside had put that prediction note there, put it there at the time that they killed Kelly. That note was a little extra piece of drama that you could not resist, Ms Hennessy. You were desperate to maximize your price for footage of the final week, and yet you knew that with each passing day the murder grew colder and with each eviction the chances of the killer still being in the house lessened. Hence your absurd, ridiculous note, a note which fooled the world but which served only to convince me that there definitely would not be another murder.”

“Excuse me, sorry to interrupt, babe.” It was Chloe again, delighted to have another chance to get into the action. “They’ve asked me from the box to ask you to tell us how she did it. I mean we’ve got as much time as you like, but the problem is that we’re live and at some point we have to cut to an ad break, but we do all really really want to know.”

“Justice has its own pace, miss,” said Coleridge grandly. He was grimly aware that he had no proof. If he was to gain a conviction then he needed a confession, and only Banquo’s ghost, only a set of shaking gory locks, could get him that. The time had to be right, the killer had to sweat.

“Fine, babe,” said Chloe. “They say it’s cool. Respect. Whatever.”

“Surely you must all have guessed how she did it anyway?” said Coleridge. “I mean, isn’t it obvious?”

The sea of blank faces in the audience was most gratifying.

“Ah, but of course, I was forgetting. You have not had the privilege as I have of visiting Shepperton Studios, a place where an exact replica of the house exists. A place where Geraldine Hennessy made a video recording. A recording of a murder that was yet to happen.” Coleridge had abandoned all pretence at quiet reserve. He was an actor now, an actor in a smash hit.

“One dark night shortly before the House Arrest game began, Geraldine Hennessy crept onto the set of her replica house. With a crank and a clang she turned on the studio lights and activated the remote cameras that would shortly thereafter be installed in the real house. She also pushed one manual camera into position in front of the lavatory door, where she locked it off, just as a month or so later she would instruct Larry Carlisle to do. Then Ms Hennessy stripped naked and put on a dark wig, a wig that was the colour of Kelly Simpson’s hair. She then entered the replica lavatory, where she was recorded by the only camera in the room, high above and behind her. Swiftly she sat down and put her head into her hands, not a difficult deception to pull off – the foreshortening quality of an overhead camera angle would make any differences in height and figure an irrelevance, and, when looked at from almost directly above, one hunched figure on a lavatory looks much the same as another. So, a month or so before it actually happened, Kelly’s final trip to the lavatory had been… I can’t say reconstructed – I’d therefore better say preconstructed.”

Coleridge was having a wonderful time. Banquo’s ghost was waiting in the wings, Macbeth (perhaps he should say Lady Macbeth) stood before him in all her arrogance; all he had to do now was bring her to the point where her spirit collapsed, and he truly believed he could do it. In thirty-five years of dedicated and usually successful police work, Coleridge could never have been said to have shone. But on this night, as he neared the end of his long career, he was sparkling.