When Shawn is attacked by the Nova Group, a shaken Isabelle decides to seek revenge. Meanwhile, a youthful 4400 offers Alana some information about a tragic incident from her past.

Tom and Diana are forced to cooperate with Dennis Ryland in order to find Gary Navarro of the Nova Group, and they soon discover that someone at the 4400 Center may be helping Gary hide out. Meanwhile, Shawn and Isabelle's relationship grows complicated.

Tom and Diana are drugged with a hallucinogen, created by a 4400, that causes them to confront significant people from their pasts.