A mad doctor performs a head transplant on an injured criminal, which results in him being even more dangerous and murderous than before.
- Release Date: January 1, 1973
- Runtime: 87 minutes
- Production countries: France, Spain
- Original Title: Las ratas no duermen de noche
- Original Language: español (Spanish)
Actors: Paul Naschy, Silvia Solar, Olivier Mathot, Evelyne Scott, Claude Boisson