Still haunted by a horror movie scene I accidentally saw as a kid: kids jailed under stairs/a woman boiling to death in a bathtub?

About 20-25 years ago I was around 5 years old. I was flipping through the TV and I came across a scene from a horror movie that has terrified me ever since. Would love to re-watch it now as an adult so I can finally stop having nightmares about it:

There is an old man pulling a young woman down some stairs into a basement. I think she is in a long nightgown and has long blonde hair.

Underneath the staircase is a make-shift jail with iron bars. There are children reaching out screaming desperately. I (think) their hairstyles were afros, and maybe one of the children looked similar to a young Michael Jackson.

The old man then walks the young girl over to this (claw foot?) bathtub and forces her into either a pool of acid or boiling water, and she screams and (presumably?) is boiled alive...

Any help with this would be awesome! My 5-year-old self would greatly appreciate it.