Le Prête-nom

A playwright of note, Darius developed a drinking problem after his first major hit, and has taken time out from writing his follow-up to go to a clinic and dry out. After his release, Darius finds his producer has hired a leading lady for his next show, booked the theater and advertised the starting date -- all without Darius writing so much as a word of this new play. Darius desperately tries to come up with ideas, but nothing comes to mind, with an inflexible deadline staring him in the face. One day, Darius kills a neighbor's cat by accident; terribly depressed, he swallows some sedatives and falls asleep at his computer -- only to awake with the beginning of his play glowing on the screen. Darius is now convinced he must kill in order to create, and starts murdering an ever-expanding variety of creatures in order to satisfy his now bloodthirsty muse.

A workman finds a singing frog in the cornerstone of an old building being demolished. But when he tries to cash in on his discovery, he finds the frog will sing only for him, and just croak for the talent agent and the audience in the theater he's spent his life savings on.