A New York detective tracks a serial killer who injects his victims with poison at Grand Central Station.

After a 17-year-old shoots his parents dead and then turns the gun on himself, an investigative reporter makes a disturbing discovery. The adopted boy was born to a mother who, as a teen, inexplicably murdered her parents as well. Even more alarming is the discovery that the dead boy has a twin, who may also be genetically predisposed to kill.

Just after he turns sixteen, Robert finds out that he is adopted. His parents find to their horror that he was kidnaped from his real parents. They decide to tell him about this, even though they fear they might lose him. Robert runs away to find his real parents. He finds and gets close to them, without revealing his true identity. Eventually he must decided where he belongs.

In a seaside suburban paradise, four married couples struggle with the conflicts and passions that buffet every marriage.