Trapped in London due to the fog, lawyer Everard Logan (Laurence Olivier) grudgingly allows the use of his hotel sitting room by a stranded partygoer, Leslie Steele (Merle Oberon). Charmed by Leslie even after she tricks him into giving up his bedroom and pajamas, Everard becomes infatuated, despite his suspicion that she is married. When Lord Mere (Ralph Richardson) engages Everard to file for divorce against his wife, who met a man at the hotel, Everard fears he may be the "other" man.