Someone is targeting young 4400's and Maia gets kidnapped. A mistake from Shawn's past comes back to haunt him. Richard is given a position of authority at the 4400 Center.

Tom and Diana continue to investigate the disappearance of the 4400 children. Isabelle and Shawn's relationship becomes public.

Tom and Diana must race to find the source of a computer virus that could bring down Ubient software, one of the world's largest software companies that is run by suspected member of the marked, Drew Imroth. Meanwhile, Maia visits Promise City where she receives an unexpected birthday surprise: a visit from her birth parents.