A man is killed in his own home during a candlelit dinner. Suspicions are concentrated in two directions: the man's ex-wife and the infamous "Pimpernel Scarlet", a professional theft, who lures men through some marriage agencies. Captain Anceschi and Marshal Cecchini investigate the "Lonely Hearts" agency while Don Matteo, worried about Pippo, who has decided to move in with his new girlfriend, begins to shed light on the murder. The culprit turns out to be the owner of "Lonely Hearts", who is in love and jealous of Gloria, a young woman who is his accomplice in the agency's scams, when faced with the news of the love that has blossomed between her and a client, and her following don't work for him anymore, he killed the woman's lover during an argument....
