After the mayor uses a potentially dangerous substance to protect the local plantation, the lakeside town of Mountview, in California, is attacked by a lethal species of large cockroach. After some of the town's inhabitants are killed, the mayor enlists the help of eccentric pest exterminator General George S. Merlin in order to prevent further harm to the local dwellers.

An undercover cop in a not-too-distant future becomes involved with a dangerous new drug and begins to lose his own identity as a result.