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Watchers is a novel written by the best-selling author Dean Koontz, released in 1987. A film adaptation was released in 1988.
On his 36th birthday, Travis Cornell woke up at five, and went hunting. While out in the woods, he meets a dog who will change his life. With this dog, he flees from an enemy he doesn't see, to fight a battle he doesn't want to fight. Along the way, a woman with a terrible past, and a hit man who kills for fun, will get dragged into the final confrontation with the Outsider.

Plot Summary:

Travis Cornell, a retired Delta Force soldier, stumbles upon a dog while hunting out in the woods. Travis and the dog end up fleeing from an unknown predator, and Travis ends up adopting the dog as his own. Travis names the dog Einstein, due to what he perceives as its unusually intelligent behavior. Over the next few days, Travis learns that Einstein is much more intelligent than he originally thought; in fact, Einstein is sentient, and possesses a human-level intellect, possibly capable of reading and spelling.

Meanwhile, Travis meets and is drawn to Nora Devon, a kind but self-loathing woman who lacks social skills due to her sheltered upbringing by her cold, cruel aunt. With Einstein's help, Travis manages to draw Nora out of her shell, and the two form a relationship.

Unfortunately, Travis learns from Einstein that he is being hunted by a monstrous creature, the Outsider. Einstein was a product of a government experiment into improving animal intelligence, the ultimate goal being to create an intelligent dog to be used as a spy. The creature is another product of the experiment, an ape-like monster designed to be a weapon of war. The monster is driven by an uncontrollable instinctive hatred, but is also self-aware; it hates itself for its horrible nature, and also hates Einstein for being the "favored son" of mankind. Like Einstein, the Outsider has escaped from the project and is now intent on tracking and killing Einstein.

Einstein is also being hunted by a megalomaniacal hitman named Vincent Nasco. Vincent, a killer for the Italian mafia, believes that he has the ability to absorb the life-force of others by killing them; his ultimate goal is to become immortal. Vincent was hired by the Russians to kill the American scientists associated with the project that created Einstein and the Outsider. Along the way, he disobeyed orders and interrogated his victims, learning about the true nature of the project and the existence of Einstein.

Travis, Einstein, and Nora flee from place to place from the Outsider as well as the US government, while unknowingly being tracked by Vincent. The three protagonists manage to escape the government by creating new identities for themselves, but must confront Vincent and the Outsider in a final confrontation in a remote mountain cabin.