Sara and Greg become quarantined after entering a crime scene that is contaminated with a deadly pathogen.
While Wade gets advice from Jessica on winning Marion back, Stuart gets to know some construction workers.
Castle and Beckett must reconstruct the 47 seconds prior to the time a bomb exploded at a protest rally in order to find who planted the bomb.
When a PHD member's loved one is shot and killed, the entire team takes it up a notch to solve the crime before the team member does.
Meanwhile, Brenda must tame her temper when her nemesis, reporter Ricardo Ramos, accuses the PHD of working only on high-profile cases.