Tom Bates (Denholm Elliot) is racked with guilt over causing his daughter, Patricia (Suzanna hamilton), to be an invalid (she accidentally ran into an oncoming truck after catching him and his secretary having sex), so he reluctantly invites a young man home to dinner whom he mistakenly believes is his daughter's old school friend.

Mrs. Bates (Joan Plowright) finds their visitor, Martin Taylor (Sting), quite charming and welcomes the change in the long and arduous work of taking care of their daughter, so she invites him to stay for a few days. Mr. Bates is quite leery of Martin, but in the interest of keeping peace with his wife and trying to keep his guilt in check, he agrees to let him stay.

Martin slowly exploits the Bates' trust as he hatches an evil plot that will change all of their lives.