Its creator was “ashamed” and “embarrassed”. “No one will ever see it.” It was “bad, bad, bad”.

The film that triggered this outpouring was Jerry Lewis’s catastrophic Holocaust drama The Day the Clown Cried. Shot in the early 1970s, it has notoriously never been officially released in any form, and only tiny snippets of footage have ever made their way into the public arena. Lewis, at that point in his career, was trying to reinvent himself after his zany-comedy persona of the 50s and 60s was no longer so popular.

He got interested in the project and cast himself as Helmut Doork, a down-at-heel clown who ends up in a Nazi death camp where he leads 65 children into the gas chamber. The story behind the notorious production is told in From Darkness to Light, a new documentary directed by Eric Friedler and Michael Lurie and premiering at the Venice film festival, which promises to at last get to grips with the mysterious story of why The Day the Clown Cried was never shown in cinemas. Toe-curling clips explain at least part of the reason, with Lewis’s clown pretending his nose is caught in barbed wire to amuse the kids, and doing a Pied Piper routine at the gas chamber door; these suggest he was right to keep The Day the Clown Cried off the screen on taste grounds alone.

There were also familiar industry reasons behind the picture’s abandonment: contractual disputes, wrangles with producers and writers, money problems and creative differences. Most cruciall.