On their quiet farm, Sam Philips and his young son Tony Phillips are tossed into a perilous mystery when a bright light suddenly grabs Sam and vanishes him from sight. Three years pass, and the same radiant force returns, planting a seed in a nearby forest. From that seed arises a half-human, half-alien creature that is struck by a car, killing the couple inside. The creature then makes its way to a cottage nearby, where it attacks and impregnates the woman living there before dissolving. When she awakens, her belly swells at an alarming pace until she gives birth to a fully formed Sam, who kills her. The newborn Sam washes himself, steals the driver’s clothes, and slips away in the car.
Now in London, Sam Philips tracks down Tony, who lives in an apartment building with his mother Rachel Philips, her new American boyfriend Joe Daniels, and French au pair Analise Mercier. Tony endures recurring nightmares of blood, and Sam re-enters their lives, moving in despite Joe’s misgivings and claiming memory loss. After Tony witnesses Sam drinking the eggs of his pet snake, Sam consoles him and drinks his blood, and the boy discovers he has unsettling paranormal powers.
Those powers grow quickly. Tony uses them to dispatch a neighbor who harmed his snake by sending a life-sized toy soldier to attack, and he even brings a toy clown to life. Sam and Rachel visit the old farm where they once lived, leaving Tony in Analise’s care. During a game of hide-and-seek, Analise is knocked out by the clown and used as a womb for alien eggs. Tony then commands a toy tank to assault his friend Michael, who is killed by a panther as he tries to flee.
Meanwhile, Sam and Rachel share a moment of intimacy at the farm, and his skin begins to bleed and decompose, revealing the full extent of his alien nature. Joe takes Tony to the farm, where Sam leads his son up a hill toward the alien light. Sam, now taking the form of an alien, unleashes a terrifying scream to kill Joe Daniels, and he and Tony step into the light, returning to the alien world and leaving Rachel behind.
Back home, Rachel, now pregnant with Sam’s alien second child, discovers that the eggs have hatched into multiple clones of Tony. The clones approach her and gently rub her pregnant belly, and the film closes with Rachel’s quiet, knowing smile as the strange new world looms ahead.
