It's been called "the best movie Warren Beatty ever starred in." It's a very arty and well done almost surreal crime story about a drunk comedian from Detroit who wakes up and finds out he owes the mob an unspecified but really huge sum of money. He runs, becomes a hobo and ends up in Chicago. In a junkyard he sees some bums beating up a guy and snatches his social security card. He seemingly gets chased by crushed cars and machinery as a cop narrates about how you can dispose of a body. He goes to work in a kitchen where the boss can't pronounce the complicated foreign name on the card and just calls him "Mickey One."
Soon, he starts doing comedy again in clubs with a band and a piano, but when his career starts to take off he gets scared the Detroit mob will find out about him. Is he going to trash his big break out of being paranoid? Is the naive girl he met going to shoot her mouth off and give him away?
There's also a Japanese guy who appears all through the movie beckoning him who eventually does a wild piece of performance art with a huge white Rube Goldberg device that catches on fire and the fire department comes and sprays foam all over everything.