Pip intends to throw out her murder board because Elliot Ward has been arrested and she is supposed to be finished with the investigation. Instead, while getting ready for the fireworks, Pip is pulled back into the evidence and removes only the clues that led to Elliot: the Ivy House Hotel, the planner number, the hit-and-run, Sal’s stolen alibi, Max’s photo, and Unknown’s printed threats.

As Pip redraws Andie Bell’s movements on a map, Pip realizes Elliot’s estimate of the timing must be wrong. Becca Bell’s account is supported by CCTV showing Andie driving through the high street at 10:40 p.m., meaning Andie likely went from home to Elliot’s house and left afterward with a head injury. This makes Elliot, not Becca, seem to be the last confirmed person to see Andie alive, but it still does not explain how Andie’s blood ended up in the car boot near Howie Bowers’s house.

Pip then recognizes an important contradiction: there were two killers, but the threats to Pip had not all come from Elliot. Remembering Elliot’s confused reaction when Pip accused him of killing Barney, Pip compares the printed notes with Unknown’s texts and sees that the tone and methods differ. Pip concludes Elliot sent the subtler threats, but Unknown—the person who smashed her laptop and killed Barney—must be Andie’s real killer.

Pip sends her family ahead to the bonfire so she can keep working. Alone with the board, Pip reviews when Unknown contacted her and worries that Andie’s real killer may seek revenge now that Elliot’s crimes and Sal’s innocence are exposed. Pip rules out Jason Bell after remembering his genuine grief, anger, confusion, and faint hope when police contacted him about the girl Elliot had hidden.

Looking again at the Bells’ family photo, Pip begins connecting earlier evidence: Stanley Forbes’s comments, Emma Hutton’s interview, Jess Walker’s account of the Bells, Max Hastings buying drugs, Howie’s supplies, the calamity-party drink spiking, the missing burner phone, and Elliot’s timing. Pip realizes the last person to see Andie alive was not Elliot after all, but Becca Bell.

To confirm the final missing piece, Pip phones Max Hastings, records the call, and threatens to tell police about the hit-and-run cover-up unless he answers. Max admits he put Rohypnol in Becca’s drink and had sex with her at a calamity party in March 2012, though he denies it was rape. Pip hangs up with the recording and understands the consequences: Max’s assault on Becca is tied to Andie’s death, and Pip decides what she must do next.