Although it was not actually made by Hammer Film Productions, The Creeping Flesh is packed full of Hammer horror regulars. Christopher Lee and Peter Cushing star in it, Freddie Francis directed it and Michael Ripper also shows up.
Cushing plays Emmanuel Hildren, a Victorian scientist who has come into possession of a skeleton that seems to belong to an unknown ancestor of Homo sapiens. When he learns the skeleton can regrow its flesh when it touches water, he does research into the myths from the area where it was found and finds references to evil giants. Emmanuel decides he can use the skeleton to create a serum that will kill evil itself, but there are unforeseen side effects.
If that sounds interesting to you, I probably explained it wrong. The plot of this movie is an absolute mess. On top of the skeleton that grows skin and all the scenes of people looking through microscopes and talking about evil, there's also a subplot where Lee plays James Hildren, the brother of Emmanuel who ran an asylum where Emmanuel's wife had been committed until her recent death, and the two brothers are both competing to win the prestigious Richter Prize (which doesn't seem to be an actual thing from history) and also Emmanuel's daughter is angry because the fact that her mother had been alive in an asylum was hidden from her her whole life. I never understood what the serum was in the first place, so the added tension between characters just made things harder to follow. There are some good special effects in the movie, but I can't really recommend it.