Italian zombie horror. After a scientist (Raimondo Barbieri) studying an ancient crypt inadvertently revives the nearby dead, he is quickly disposed of by the reanimated zombies. Meanwhile, three couples who were supposed to visit the professor to share his latest discovery are forced to take shelter in his mansion to avoid the hordes of ravenous undead who proceed to lay siege on the building. But as night falls, the walking corpses become more intelligent and start to break into the mansion to terrorise the remaining survivors...