The 4400

''The 4400'' (pronounced "the forty-four hundred") is a science fiction television series produced by CBS Paramount Network Television in association with BSkyB, Renegade 83, and American Zoetrope for USA Network in the United States and Sky One in the United Kingdom. It was created and written by Scott Peters and René Echevarria, and it starred Joel Gretsch and Jacqueline McKenzie. The series ran for four seasons from July 11, 2004, to September 16, 2007.

Premise

In the series' pilot episode, a ball of light deposits a group of 4400 people in the Cascade Range foothills near Mount Rainier, Washington in the United States. Each of the 4400 had disappeared in a beam of green light in 1946 or after. None of them have aged from the time of their disappearance. Confused and disoriented, they have no memories of what transpired prior to their return.

Title

Creator Scott Peters has stated that the series was originally titled "A Light in the Sky", but looking for something unique he decided to "play around with numbers" instead and arrived at "4400" because it "just sounded cool" and "was a very round number with two 4s and two 0s".

Synopsis

The National Threat Assessment Command (NTAC), a division of the Department of Homeland Security, is in charge of dealing with the return of the 4400. Dennis Ryland is the head of NTAC. Ryland assigns Tom Baldwin and Diana Skouris as the lead team to investigate the 4400. In the second season, Ryland goes to Washington and is replaced by Nina Jarvis. In the fourth season, Meghan Doyle takes over as the head of NTAC.

Many of the returnees have trouble getting their lives back on track after being gone from the world for years. More significantly, a small number of the returnees begin to manifest paranormal abilities, such as telekinesis, telepathy and precognition, as well as other "gifts". For example, in the pilot, Shawn Farrell manifests an ability to heal the broken neck of a dead bird, bringing it back to life. In addition, one of the 4400, Lily Moore, has become pregnant between her disappearance and return.

The first-season finale, " White Light", reveals that the 4400 were abducted not by aliens, but by humans from the Earth's future, that Kyle Baldwin was to be their "messenger", and that they were returned to avert a catastrophe.

By the second season, it is revealed that all 4400 have a fictional neurotransmitter, promicin, in their brains, which gives them their powers. The government, afraid of what this large group would do with such power, had secretly been dosing all of the 4400 with a promicin inhibitor, which had worked on most, but not all, of the 4400. One of the inhibitor's side effects is a potentially fatal immune deficiency. The inhibitor is ultimately removed from the 4400 by a dose of promicin extracted by Kevin Burkhoff from the blood of the infant Isabelle, who was never given the inhibitor.

At the beginning of the third season, the Nova Group, a terrorist faction made up of 4400s, emerges. Originally formed as a "defensive" group in the aftermath of the promicin-inhibitor scandal, the Nova Group eventually carries out numerous terrorist attacks against the government and NTAC. The group is responsible for many terrorist attacks including the assassination of the men involved with the promicin-inhibitor conspiracy; the attempted assassination of Ryland; the framing of Baldwin for murder; and the driving of another person to insanity.

During the third and fourth season, it is revealed that only a certain faction from the future wants to see history changed. Another faction, which prefers the status quo, opposes the 4400, and has sent their own operatives, including Isabelle Tyler and "the Marked", into the past. The exact motives of both factions were not revealed.

Eventually, Jordan Collier, a returnee who declares himself the savior of humanity, makes promicin shots available to the general public. However, only half of the human population can actually tolerate promicin, and thus develop superhuman abilities, while the other half die upon taking the shot. Although the government outlaws promicin use, thousands of previously ordinary people have developed superhuman abilities, severely complicating NTAC's task. Collier later annexes a part of Seattle and transforms it into "Promise City", a self-proclaimed paradise open to all people with superhuman abilities. The US government attempts to reclaim Promise City but meets with little success.

At the conclusion of the series, Danny Farell's uncontrolled ability exposed some of the residents of Seattle to promicin, resulting in about 9,000 deaths and as many newly empowered humans, while at the same time forcing the remains of NTAC (now themselves mostly promicin-positive) to ask Jordan Collier and his followers (as the only group immune to the 50% chance of death from exposure) to become the ''de facto'' government of Seattle. The series ended with a cliffhanger, with Collier pledging to build the future he had promised, while the government watches uneasily as Collier's militia remains in control of Seattle, now known as Promise City.

Promicin

In the series, promicin is a fictional neurotransmitter the human body produces that controls and regulates bodily functions. In the 4400, it enables every member to use parts of the cerebellum no human has previously used. This is the cause of the new abilities in each returnee. Promicin's behavior and effects are unpredictable, potentially giving any ability. However, as part of a government conspiracy, every 4400 is regularly injected with a promicin-inhibitor, suppressing their potential new abilities.

Since the government ceases injecting promicin inhibitor, every 4400 develops an ability.

Dr. Kevin Burkhoff devises a way to artificially create 4400 abilities through a series of promicin injections, using himself as a test subject, giving him regenerative abilities. However, the government finds out about this breakthrough and builds up its own stockpile of a much purer promicin (extracted from Isabelle Tyler), which they in turn use to create at least one group of soldiers with 4400 abilities, as demonstrated by the government's attack on Promise City. Jordan Collier steals the government's supply, and begins distributing it via human couriers to anyone who wants the shot.

An injection of promicin has a 50% chance of either killing the person taking the injection (by way of an aneurysm) or giving them a 4400 ability. In the fourth season, Dr. Burkhoff claims to have discovered how promicin interacts with the body, thus being able to predict whether a person will survive the shot or not. It is explained that nine out of ten left-handed people who take the shot survive. In the brain there is a small part called the corpus callosum. It is essentially a bundle of neural fibres that connects the two hemispheres and it is usually slightly larger in left-handed people than it is in right-handed people. That is why left-handed people survive; the size of that part of the brain helps determine whether or not a person will be able to integrate a new neurotransmitter. With further research, Dr. Burkhoff believes a simple CAT scan will be able to tell how anyone's body will react to a promicin shot.

There exists a substance that can eliminate all traces of promicin in the human body, effectively robbing the injected individual of any 4400 powers and in addition making this person allergic to promicin. The identity and makeup of this substance is not stated, and the only known source of it so far is from the future. A second method also exists for removing promicin from non-4400 humans, through the promicin-neutralizing ability of Jordan Collier.

There also appears to be a substance that can counteract the anti-promicin's effects as Tom Baldwin, during his time as a member of the "Marked", uses this substance to help Isabelle Tyler regain her powers by removing her promicin allergy. Like the anti-promicin, this substance appears to be from the future.

As discovered by Marco in the episode The Starzl Mutation; Seattle Presbyterian Hospital started using a flawed radiation machine to treat their cancer patients in 1969. The microswitches that controlled the machine were not functioning properly, so the doses were incorrect. This went on for just under five years. Once the hospital figured out what they were doing they tested everyone who had ever been exposed to it and in some cases the radiation induced a small mutation. This mutation was a slight alteration of the eleventh chromosome, named the "Starzl mutation" after the manufacturer of the faulty machine.

The mutation is hereditary, meaning people that got it passed it onto their children. The Starzl mutation is both harmless and conserved in those offspring; they live normal healthy lives. While the offspring of a returnee normally do not retain the ability to generate promicin, a second-hand report from John Shaffner (an ex-special ops soldier) suggested that the offspring of a 4400 and a Starzl mutant will be "promicin-positive", meaning they will have abilities. This is believed by Tom Baldwin and Diana Skouris to be the reason why the abductees were returned to the Seattle area – it is the only place they are likely to encounter individuals who possess the Starzl mutation and therefore the only place they are likely to produce children with 4400 abilities.

The promicin-inhibitor "piggybacks on glucose", after entering the brain through facilitated diffusion. It is a binding protein; that is, it binds itself to promicin in the body and neutralizes it. However, if there is no promicin for it to bind to, it remains in the body. Eventually, it builds up to toxic levels in the lymph nodes, damaging the immune system. The result is a chemically induced immunodeficiency.

To counteract the promicin inhibitor, Dr. Burkhoff develops a serum containing Isabelle's pure promicin. This serum neutralizes the charge so the inhibitor is not able to cross membranes and can be flushed out of the body.

Setting

''The 4400'' is set in Seattle, Washington, United States, but actually filmed in the Vancouver, British Columbia, Canada, area. Settings include:
*Promise City: founded by Jordan Collier with the guidance of Kyle Baldwin. It is created as a haven for people who are promicin-positive (P-positives), and also serves as the base of Collier's movement to spread promicin to the world. Collier intends for Promise City to be a model for the future, and the first stage to creating "Heaven on Earth". Though the characters claim that the location is on the Duwamish River