 Steve and especially Mark Sloane watch the reality show Hothouse because med student Alex Smith, their friend, is a participant to pay off some of his study loans. Then Larry, the generally hated,  creepy  contestant who was about to be voted out, is murdered by a female contestant who poisons him from the roof with an OD of his normal anti-depression medicine, which he often mixed with vodka despite Alex s warnings. It looks like a suicide or accidental overdose, but Alex uses the  diary room  to pass the message that Steve must continue the investigation, as Larry was in no measure depressive. Mark notices a suspicious draft on the unaired tapes, and goes in as Larry s replacement to snoop. He investigates the camera angles, which allow some un-noticeable moves, and catches Nora looking in the closet space for diamonds Larry would have promised her; Steve finds a tape which shows she picked up an earring from the floor next to her lover Larry s corps. After Jamal advised her not to talk to Steve without a lawyer and seeing him examine the skylight, Nora realizes Mark is a plant, and calls a house meeting to expel him. He gets everyone to participate in an experiment that night sleeping in different rooms, when he reenacts the killer s method he recognized from a movie, and explains to everyone what happened, backed up by some details on crucial tapes...