Tom and Diana continue their search for a mysterious kidnapper who is targeting 4400 children, while Shawn's relationship with Isabelle causes concern at the Center.

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.