A computer whiz named 'Bean' is among several people found dead with strange striations, odd puncture wounds and missing internal organs. Bean's brother Ted teams up with detective Gina to get to the bottom of it. With the help of a computer hacker, they find a blueprint that reveals the killer who has been terrorizing the city...a rampaging posse of genetically mutated cockroaches!
A disease carried by common cockroaches is killing Manhattan children. In an effort to stop the epidemic an entomologist, Susan Tyler, creates a mutant breed of insect that secretes a fluid to kill the roaches. This mutant breed was engineered to die after one generation, but three years later Susan finds out that the species has survived and evolved into a large, gruesome monster that can mimic human form.
Police lieutenant detective Thomas 'Thom' Randall's steady girl-friend, Dr. Jennifer 'Jen' Allen, is Dr. Aaron Michaels's main assistant on his pharmaceutical firm Bellion's research program to cure the highly contagious, fatal infection Guinin. A convicted murderer, whom Thom arrested, is one of their special drug test subjects, but escapes. The convict and Jen are affected by radioactively altered DNA from an experimental reactor used on mosquitoes which transfer quinine. The convict soon mutates into a mosquito-like monster, which sucks its victims dry. By the time Thom and his junior murder brigade partner Charlie Morrison figure out what happens, Jen starts mutating herself.
A cop on the track of a criminal finds himself in the midst of an unfinished subway tunnel, when his flashlight reveals a startling discovery: a three meter long scorpion-like Bug. With one slice of its massive tail the bug fells the man and devours him. FBI agent Matt Pollack is brought in to investigate, and when forensics reveal the source of the problem, he turns to his friend and entomologist Emily Foster for help.