This is the most infamous train wreck in Hollywood history and also one of the most legendary lost movies. There have been many an essay and books dedicated to the subject but essentially this was a terribly misplaced attempt at doing a serious Holocaust movie about a Jewish clown who leads kids into the gas chambers while incorporating Jerry Lewis’ usual schtick.
To explain this for Zoomers: imagine watching Schindler’s List starring Seth Rogan. That’s kind of what this is.
The movie was never completed because of a rights dispute (the author of the book wasn’t paid and the financiers took off into the night leaving Jerry Lewis alone to helm the project) and every couple of years there would be whispers that Jerry was trying to complete the movie but it never happened.