Tom is torn between duty and family when he discovers the identity of Jordan Collier's assassin; and Liv stirs up tensions between Danny and Shawn at the 4400 center.

A 4400 terrorist marks the dead Jordan Collier's birthday by planting a device within NTAC that causes all the males to turn savage, forcing a lockdown of the facility. Meanwhile, Lily suspects the 4400 Center has devious plans for Isabelle; Shawn adjusts to being a media figure; and Kyle kindles a romance.

In Nina's absence, Dennis Ryland oversees Tom and Diana's investigation of a deadly epidemic affecting the 4400. Meanwhile, Isabelle is examined without Lily's consent; Alana begins confusing reality with the fantasy she shared with Tom; and an ailing Shawn abdicates control of the 4400 Center.