An entire town of dead people leads Tom and Diana on the grisly trail of Jean DeLynn Baker, a 4400 who has the ability to grow toxin-emitting spores on her hands. It seems Jean has come to the conclusion that the lethality she now possesses is not a curse, but is instead a gift that enables her to "purify humanity." Meanwhile, Matthew Ross joins the 4400 Center as an advisor to Shawn, who has become overwhelmed with a deluge of letters seeking help now that his healing powers have been made public. The Center also finds Lily trying to keep Isabelle at peace while she adjusts to her introduction to her halfsister Heidi. Elsewhere, still unaware of his role in Jordan Collier's assassination, Kyle reconnects with Wendy; and Diana leaves Maia in the care of her sister, who crosses the line and uses Maia's pre-cognitive abilities for profit.