Killer slugs on the rampage in a rural community.

Siren II, a submarine under the command of Capt. Phillips, ventures into the deep on a mission to recover the missing Siren I. Their quest is hindered when the submarine becomes entangled in a patch of toxic seaweed.

A group of drug dealing petty criminals fleeing from the police take a magician and his daughter hostage; but once they reach his mansion, all hell breaks loose.