Sir Stafford Nye's flight home from Malaya takes an unprecedented twist when a young woman confides in him that someone is trying to kill her. In a moment of weakness, he agrees to lend her his passport. Unwittingly, the diplomat has put his own life on the line. When he meets the mystery woman again, she is a different person, and he finds himself drawn into a battle against an invisible—and altogether more dangerous—enemy. . . .