Its plot follows the creation of a genetically modified insect, designed to battle an infected cockroach infestation, that rapidly evolves and begins attacking humans.

Unable to develop a cure for the disease, Dr. Peter Mann, deputy director of the CDC, recruits entomologist Dr. Susan Tyler.

Dr. Tyler uses genetic engineering to create the "Judas breed", a hybrid between a mantis and a termite that releases an enzyme which accelerates the roaches' metabolism.

Initially, she believes that this is impossible since the specimens she released were all female and designed with a lifespan of only a few months, which should have ensured that the breed would die off after a single generation.

Manny also enters the tunnels in search of Chuy and comes across Susan, whom he rescues along with Peter and Leonard, and they barricade themselves inside a train car.

Susan projects that the Judas will spread throughout the tunnels and overrun the city unless they manage to kill the colony's single fertile male.

While trying to reach the track switches, Manny finds Chuy who has survived due to his imitating the clicking noises the bugs use for communication.

Leonard's injured leg starts bleeding heavily and knowing the smell will incite the creatures and endanger the group, he creates a diversion that allows the others to get away, before being killed.

He is chased into a room where hundreds are nesting and blows them all up by setting fire to a loose gas pipe, before diving underwater to safety.

The character of Manny was originally written by Guillermo del Toro for one of his favorite actors, Argentinian Federico Luppi, whom he directed in Cronos (1993).

[9] Miramax and Dimension Films bosses Bob and Harvey Weinstein repeatedly clashed with del Toro over creative differences.

[12] Following an intervention from lead actress Mira Sorvino, Weinstein backed down, and principal photography would be completed with del Toro as director in early 1997.

Rack later compared making the film to "being a prisoner of [a] war camp",[12] while del Toro stated in 2018: "The only time I have experienced bad behaviour, and it remains one of the worst experiences of my life, was in 1997, when I did Mimic for Miramax.

The website's consensus reads: "Mimic finds director Guillermo del Toro struggling to inject his unique sensibilities into a studio picture – and delivering just enough genre thrills to recommend.

[19] Roger Ebert gave the film three and a half stars, saying "Del Toro is a director with a genuine visual sense, with a way of drawing us into his story and evoking the mood with the very look and texture of his shots.