The fourth season of The 4400 ran from June 17 to September 16, 2007. Like the previous two seasons, it featured thirteen episodes, but there was no two-hour premiere. On December 18, 2007, it was announced that due to the ongoing Writers Guild of America strike, budgetary problems, and lower-than-anticipated ratings, The 4400 had been canceled and would not be returning for a fifth season, despite the fourth season's cliff-hanger.
Shawn Farrell's political ambitions are threatened by a woman who claims he healed her mother in return for sex. At the same time, Jordan Collier annexes part of Seattle itself and calls it "Promise City", threatening to retaliate if opposed.
Opposing sides all wake up inside NTAC without any memory of how they got there. A lockdown at NTAC traps everyone, including Collier and his group, and everyone must put aside their differences and work together in order to find a way out.
Richard surprises Isabelle when he shows up in Promise City... but the happy reunion takes a turn when Richard kidnaps her in hopes of starting a new life with his daughter. Meanwhile, Tess, her schizophrenia out of control, uses her ability to take control of people at a diner, forcing Kevin to call Shawn for help.
Tom has trouble focusing on the hunt for Richard Tyler because of dreams he's been having about the future. Richard, in hiding with Isabelle, is visited by his wife, Lily who has been dead for over a year. Meanwhile, Jordan Collier's movement is threatened when Shawn announces that he is working on a test with Kevin Burkhoff that would tell people whether or not they would die if they took a shot of promicin.
Meghan Doyle and Diana discover a way to extract the future entity out of Tom, which could cost him his life. Meanwhile, Shawn recruits a small band of promicin positives to bust Kevin out of Promise City. Isabelle delivers Jordan Collier into the hands of The Marked.