As the reappearance of 4,400 missing persons on a single day confounds the global community, federal agents on the case slowly discover the ways in which the victims have been changed.
Cast: Jacqueline McKenzie, Joel Gretsch, Patrick John Flueger, Conchita Campbell, Chad Faust, Richard Kahan, Mahershala Ali, Billy Campbell, Megalyn Echikunwoke, Samantha Ferris, Kavan Smith, Laura Allen
Danny Farrell's newfound ability to spread promicin leads to several hundred deaths, including his mother. With Seattle in chaos, NTAC is forced to accept Promise City's offer of help.
Marco finds a way to get the old Tom back, but it is dangerous and they don't have a very long time.
Malfunctioning ATMs lead Agents Baldwin & Skouris to a man who made threats against a large tech firm. The Marked make appearances.
Richard and Isabelle are pursued by NTAC. Elsewhere, a test is developed that determines if people can be killed by promicin.
Tess's schizophrenia gets out of control, and Shawn is asked to lend a hand. Richard Taylor tries to get his daughter back, and he has a surprise for her.
A lockdown at NTAC threatens the lives of Tom, Diana, Meghan, Shawn, Kyle, Jordan, Isabelle, Maia, Marco, PJ and Brady when they wakeup inside the building with no recollection of how they got there.
Shawn gets bad publicity when he ends up having sex with the daughter of a woman whom he cured and it turns out to be a trap when the girl tells the media her story.
The NTAC nerd squad bring to their Director's attention a 4400, Curtis Peck, who was a shoestring budget film maker and continues to be one, except that his 4400 ability seems to be to receive script pieces that combine to tell the true, complete answers to haunting questions, like "What happened to Jimmy Hoffa?" and "Who shot JFK?"
Now that he knows Kyle is Promicin Positive ("P+"), Tom sets out to track him down. His journey leads him to a town that is no longer on the map and the people of which are not ordinary.
Diana catches her sister April, who has survived a promicine shot and gained an ability the full potential of which she fails to grasp - to make anyone answer truthfully to any question posed by her.
After taking promicin, an old lady named Audrey Parker develops the ability to astral project from her body. When she's murdered, her spirit tries to reach Tom and Diana to help them find her killer.
Diana returns from Spain. NTAC tries to identify the person whose ability makes people's worst fears come true. Shawn returns home from the hospital and his brother Danny tells him that he's thinking about taking promicin.
A high school kid named Graham develops an ability which makes people worship him to the point of sacrificing their lives for him. Tom visits Isabelle in jail, hoping to get information on the whereabouts of Alana who's been missing for months.