Hotchner and Gideon must move quickly to save Elle and the other passengers taken hostage on a train by a delusional fellow passenger who threatens to kill them all.

When a paranoid schizophrenic passenger has a delusional episode on board a train, Hotchner and Gideon must play into his fantasy in order to save the people he has taken hostage. To that end, they send in Dr. Reid who tries to convince the man that he agrees with his skewed view of the world in order to get Elle and the other passengers safely off the train.