Ty Upshaw

Martha and Castle are held hostage by bank robbers dressed in hospital scrubs; Beckett's rescue efforts are hindered by a strict hostage negotiator (Dean Norris).

When Tony opens a letter releasing a mysterious powder from inside, he and Kate are put into biohazard isolation as a precaution.

The agents search for a killer who seemingly possesses the ability to see through walls.

Jack finds Kyle Singer's residence, but Kyle, unknowingly in possession of the deadly virus, is gone. Meanwhile, as President Palmer prepares himself for the upcoming televised debate, Wayne forces him to consider some serious allegations against Anne which have surfaced; and a technical specialist (guest star Andrea Thompson) is brought in by CTU to play a critical role in dealing with the viral threat.

Detained by the police, a developer shows Catherine a woman's finger in a tin, prompting a kidnapping investigation.

Warrick investigates a drive-by shooting in his old neighborhood; Nick follows up on the murder of an Internet company worker.