Based upon a short story by Donald A. Wolheim, Mimic gives us an apocalyptic vision of the near future, where an epidemic disease, carried by cockroaches, threatens to kill virtually all the children in New York City. However, scientist Dr. Susan Tyler (played by Academy-Award winning actress Mira Sorvino) offers a solution. By combining the DNA of various species of cockroaches, she has created the "Judas" breed. This breed has a metabolism set at light-speed--that is, the cockroaches breed, create sterile offspring, and promptly burn out within just a few days time. She unleashes her genetically-engineered cockroaches in the New York sewer system and the plan works to perfection. The floor of the sewer system is soon filled with dead cockroaches. The children of New York City are spared and Dr. Susan Tyler is a hero. But that's just the beginning of the story. It seems that the "Judas" breed didn't die out completely. Some survived--with a metabolism that pushed them through thousands of years of evolution each month.

Director Del Toro has created a truly scary and plausible vision of science run amok. Dr. Tyler's tinkering with genetics has indeed provided a short-term solution to combating a deadly disease. But at what cost? "We don't know what we did!" says Dr. Tyler. Eventually, Del Toro takes us head first into the sewer system to confront the horror breeding below the streets. Until then he keeps us off balance by chopping up the frame and creating an ominous sense of shadowy, unknown terror. But he also plays off of a very real sense of revulsion that most people feel about cockroaches and other denizens of the sewer. He gives us a world above ground filled with trash and decay, where diseases breed and spread at staggering speeds.

When Del Toro finally takes us underground, he gives us a huge abandoned subway platform. In short, he gives us a nostalgic world that's actually cleaner than the world above ground. But this is where Dr. Tyler, her husband Dr. Mann (Jeremy Northam of Emma), an MTA cop (Charles S. Dutton), and a CDC assistant (Josh Brolin) confront the underworld horror head-on in some harrowing (albeit predictable) scenes that evoke memories of Alien. While Mimic suffers somewhat in comparison to Alien, it still provides a powerful sense of an ominous and powerful off-screen force.

Del Toro also aims to give Dr. Tyler some depth by suggesting that she and her husband have been trying for a child of their own without any luck; and therefore he places Mira Sorvino in the Sigourney Weaver role as surrogate mother of a boy she discovers hiding in the sewer. But this development simply rips off Aliens in relatively mundane, mechanical, and predictable fashion.

The most fascinating idea contained in Mimic is suggested by the movie's title. Many creatures in nature use mimicry as a way to avoid predators--a butterfly's wings take on the appearance of owl eyes; an insect takes on the appearance of a stick. SPOILERS AHEAD: The "Judas" breed of cockroaches evolves to take the form of their greatest predator--man. On a subway platform, a human-like form might linger at the far end, occasionally stepping out of the shadows. First it's there and then it's gone. Was it a man or wasn't it?

Del Toro's edgy mix of science fiction and horror works best when it's pushing in unconventional directions--as when, Dr. Tyler and the others rub blood from the creatures over their own bodies so that the creatures won't smell them. Scenes like this are guaranteed to make the audience twitter, but it's a nervous brand of laughter--that functions like a safety value to release some of the tension.

When Mimic works, it's a powerful and tense monster movie that knows how to play off of our queasiness about bugs. Mira Sorvino is never really believable as a scientist. She's certainly no Sigourney Weaver. Without a strong actor taking control, the movie becomes hollow at the core, but in the long run, it doesn't really matter. Del Toro knows how to make us shudder and that's what this movie is all about.