Eric Lazlo is doing the musical score for a movie in which the female star tries to kill the male star using a variety of poisons, poisonous insects, poisonous snakes, etc. When Eric starts to see a prostitute, Abbey, he finds his life imitating art.
Abbey has a pimp boyfriend, who wants her to keep seeing Eric out of prostitute-client arrangement until he can get to rob him. In the latter part of the film, her boyfriend enters Eric's place to rob it and fucks her in Eric's kitchen while Eric is upstairs, asking her what the noises she and Eric are making are.
Della's character in the movie that Eric is doing a musical score for is cheating on her husband. Meanwhile, Della in real life is cheating on her husband with Eric, but aside from sharing a nude massage session, we don't really see them have sex.