Alexander Sebastian lives at home with his mother until Alicia Huberman, the daughter of an old friend, turns up on a runaway horse at his riding club in Rio de Janiero. For work, Sebastian runs a secret operation out of his mansion to make an atomic bomb for the Germans in WWII.Sebastian is good at social events. Knows how to order in a restaurant, throws parties and when he catches his wife being kissed by another man. Alex is very cosmopolitan about it all until he discovers his wife is a U.S. spy. This revelation revives his need for his mother, who never liked Alicia, anyway. The family reunites to poison Alicia so Sebastian's Nazi business associates won't find out how compromised their project is.It's all so sad since Sebastian has given Alicia what Devlin won't give her: love, a home and domestic strife. Nevertheless, news of Sebastian poisoning Alicia is a game changer, so Devlin at last decides to profess his love for Alicia and give her a ride to the hospital. Sebastian stays at home with his mother. What would be a beginning for most people is Sebastian's ending. The hope that Devlin has learned something about effective dating from Sebastian keeps the end of Notorious from being a total downer.