A 4400, Curtis Peck, has the ability to expose the truth behind conspiracies when writing film scripts. In his most important film-in-progress yet, "The Marked", he promises to expose ten agents from the future- the Marked- who have taken over the bodies of prominent people in the present day. He names a previous agent in the trailer for "The Marked", Matthew Ross, and shows Ross' death at the hands of Isabelle Tyler.
Each of the Marked has an X shaped mark behind the left ear, and has no special ability of their own. Allied to the faction in the future that are opposed to the 4400, they are now trapped in the past in an attempt to complete their mission: the destruction of Jordan Collier and negation of the 4400's effect on the timeline. Before being compromised, Curtis Peck is only able to name one of the ten, the CEO of Ubient Software. After revealing Curtis' claims to Meghan Doyle, Doyle includes her suspicions in a report to DC. Tom is taken and seemingly operated on, resulting in a mark behind his left ear. The only revealed Marked meets with Tom and Diana, seemingly to feel out an alliance.