The 4400

The 4400 (pronounced "the forty-four hundred") is a science fiction TV series produced by CBS Paramount Network Television in association with Sky Television, Renegade 83 and American Zoetrope for USA Network.The show was created and written by Scott Peters and René Echevarria, and it stars Joel Gretsch and Jacqueline McKenzie. The series ran for four seasons from 2004 until its cancellation in 2007.
In the pilot episode, what was originally thought to be a comet deposits a group of exactly 4400 people at Highland Beach, in the Cascade Range foothills near Mount Rainier, Washington. Each of the 4400 had disappeared at various times starting from 1946 in a beam of white light. None of the 4400 have aged from the time of their disappearance. Confused and disoriented, they remember nothing between the time of their disappearance and their return.

The Ripple Effect

Early in the first season, theorists at NTAC suspect that the 4400s have been placed in the timeline with their enhanced abilities for a purpose, to effect some change that could propagate and redirect the course of history. An example of this was when a 4400 named Carl Morrissey attempted to use his enhanced strength to become a vigilante and prevent crime in his neighborhood park. Morrissey was killed by a group of thugs, but his death inspired others to become involved in various neighborhood clean up projects.

Another example of this effect at work came during the third season episode "Gone, Part II," in which five 4400 children are once again abducted by the future and "seeded" back into history at different time periods. Some of the "advances" accomplished by this feat included the development of artificial petroleum and composite materials used in the first lunar colonies, according to background conversations "overheard" at NTAC. These advances are negated (restoring the original timeline) in exchange for Tom Baldwin agreeing to do whatever the future asks of him, to help prevent the "disaster" to come which he learns is an order to kill Isabelle Tyler.

Tom Baldwin initially reneges on his agreement with the future humans, but the seemingly indestructible Isabelle forces his hand in the season three finale and is stripped of her abilities.