It Happened at Nightmare Inn

Eugenio Martin's horror film Una Vela Para El Diablo stars Judy Geeson as Laura, a woman who goes to visit her sister at a Spanish inn run by a pair of nuns. However, upon her arrival, Laura learns that her sister has disappeared without a trace. Laura decides to investigate, but soon develops strange suspicions about the women who run the inn, particularly after libidinous English tourists staying there also vanish.