Six teenagers go to an old remote abandoned school where 27 years ago a horrible massacre took place for a night of fun and pranks. Instead the kids run afoul of the vicious crazed security guard (excellently played with supremely creepy menace by Spanish horror icon Paul Naschy) who committed the nasty killings. Director Carlos Gil relates the intriguing story at a brisk pace and does an adept job of creating a compellingly spooky and mysterious atmosphere. The witty script by Tino Blanco and Mercedes Holgueras offers a clever and inspired blend of slasher and supernatural elements that keep the viewer guessing to the very end. The slick cinematography by Fernando Arribas makes expert use of light and shadow. David San Jose's moody score likewise does the trick. The attractive and appealing young cast all contribute lively and engaging performances, with especially praiseworthy turns by Carlos Fuentes as ringleader Ramon, Olivia Molina as the panicky Maria, Zoe Berriatua as obnoxious joker Jordi, and Carmen Morales as spunky goth chick Sandra. The murder set pieces are every bit as bloody and brutal as they ought to be. Terrific whammy of a surprise dark ending, too. A solid and satisfying shocker.