Colleen Gibson doesn't realize live-in boyfriend Dick Rasmusson, a third-rate private detective, has been cheating on her until phony psychic Madame Hugonaut inadvertently provides accurate details about his most recent indiscretion. When Colleen confronts him with what she believes is an empty gun, she shoots and kills Dick, who ironically had loaded the firearm without her knowledge. Enter Daniel Gallagher, an Irish mobster whose desire to be a crooner was dampened by his ex-girlfriend Mary when she laughed at his singing. Daniel has managed not to kill anyone in his short career as a hit man, so when he discovers Colleen has murdered Dick, who was next on his hit list, he's happy to take the credit and tell his boss and brother-in-law Jared O'Reilly that he finally completed an assignment. Unfortunately, Jared starts giving him a lot more, and Daniel enlists Colleen to do his dirty work for him. Complicating matters are Daniel's sister Ivy, who would like to see her husband dead; two bumbling detectives investigating Dick's murder; and the reappearance of Mary and her new beau, mumbling Tony Moretti.