Vivacious mystery novelist Janet Frobisher (Bette Davis) has been happily separated from her criminal husband for years. She now lives alone in a dark English country house, where she enjoys devious dalliances with her secretary's fiancé (Anthony Steel). When her husband returns out of the blue and threatens to ruin her relationship, Janet resolves to poison him. Just as she's preparing to dispose of the body, disaster strikes! Her husband's criminal cohort George (Gary Merrill) arrives looking for his pal...George wastes no time insinuating himself into Janet's home and life, and the web of tangled relationships soon develops into a macabre game of cat and mouse.