Carpenter's first low-budget horror pic for some time. Summoned to an abandoned church by a frightened priest (Pleasence), Prof Birack (Wong) finds a basement shrine dominated by a canister of green fluid. A manuscript reveals the existence of the Secret Brotherhood of Sleep, worshippers of Satan, who was entombed in the canister by his father, the evil anti-God, millions of years ago. Birack is sceptical until jets of liquid from the canister transform some of his team into malevolent zombies. Meanwhile, the embryonic Satan is struggling to release himself, and his father's power has begun to manifest itself. Refracting the traditional conflict of Good and Evil through quantum mechanics and sub-atomic physics, the sometimes talky script remains engrossing thanks to Carpenter's chilling atmospherics. The claustrophobic terror generated by fluid camerawork and striking angles is reinforced by a narrative which builds slowly but surely towards a heart-racing climax.