Dr. Jennifer Allen (Musetta Vander) in Baltimore, Maryland wants to find a cure for a disease known as the Gillen virus, a disease similar yet more deadly than the "Fire Rising virus." She and a colleague capture infected mosquitoes and give them small doses of radiation. She explains that the levels have to be exact because if the mosquitoes receive too much radiation, the results could be more devastating than the virus itself.
A convict named Ray Erikson (Matt Jordan) joins Dr. Allen's program in exchange for his lifelong prison sentence. He takes a hostage and convinces Dr. Allen to open the door to the experiment room. The security guards open fire and cause an explosion that showers Ray and Dr. Allen with the chemicals and the genetically altered mosquitoes. Ray manages to flee the scene.
He begins to transform into the titular monster, a deformed chimera, half man, half mosquito, yet he manages to find his way to his ex-girlfriend's apartment, where the process continues. When the ex comes home, she finds it in ruins. She and Ray have a short, anxious conversation before Ray's transformation is complete and he kills her.
Meanwhile, Dr. Allen returns home with her boyfriend, police officer Tom Randall (Corin Nemec). That evening, she notices her wrist is red and raw-looking. She thinks little of it, but next morning, it has spread to her entire arm. Later, while kissing Tom, she has a sudden craving for blood and bites him. He is called to Ray's girlfriend's apartment and leaves. Dr. Allen rushes into the bathroom to find her arm bleeding. She convulses, falls to the floor and her skin starts to bubble.
Tom arrives at the crime scene and is puzzled by the way Ray's girlfriend died. He is called to investigate another crime scene, where he encounters Mansquito. The monster seems unstoppable, until Tom shocks him with a stun gun, making him flee in pain. Tom's partner doesn't believe him at first but puts a bulletin out on the creature.
At the research station, Dr. Allen discovers she is also changing into a human-mosquito hybrid, but more slowly as she received a smaller dose than Ray. Mansquito appears but doesn't try to kill her, and after she faints, the monster leaves. Tom takes her to the hospital.
The doctor wants to give Dr. Allen a blood transfusion to slow down the transformation, but she replies that nothing can stop the mutation. She believes the monster sensed that she is turning into a creature like him and that once the transformation is complete, he will want to mate with her. Outside, a guard falls victim to the monster and Tom leaves to investigate. Mansquito undergoes another transformation, this time growing wings.
Dr. Allen also undergoes another transformation and alerts the officers of Mansquito's arrival. They fail to stop him. The monster heads for Dr. Allen, but she manages to escape. Tom fires a rocket launcher at the oxygen tanks behind Mansquito and assumes the creature was killed by the explosion, but that is not the case.
Meanwhile, back at the lab, Dr. Allen undergoes yet another transformation and releases the last batch of genetically altered mosquitoes, which have been perfected. Tom arrives and Dr. Allen tells him that Mansquito is still alive. She tries to commit suicide by stabbing herself with a syringe, because without a mate, Mansquito will die.
The monster arrives and Tom fights him to no avail. Dr. Allen is seriously injured by Mansquito, who is now focused on killing her rather than mating with her. Tom uses the stun gun and once again, it works. Seeing this, Dr. Allen breaks an electrical line and electrocutes Mansquito and sacrificing herself. Tom writes a report about the incident and the Gillen virus is wiped out by the altered mosquitoes.Corin Nemec as Lt. Thomas Randall
Musetta Vander as Dr. Jennifer Allen
Matt Jordan as Ray Erikson / Mansquito
Patrick Dreikauss as Detective Charlie Morrison
Jay Benedict as Dr. Aaron Michaels
Christa Campbell as Liz
Ivo Tonchev as Arrogant Swat Member
Vladimir Nikolov as Barry
Dimiter Spasov as Bellion Security Guard # 1
Ivan Urukov as Bellion Security Guard # 2
Cara McDermott as Gaffney
Peter Mechkoff as Cop # 1
Jonas Talkington as SWAT Leader
Gvenga Akukunova as Uniform Cop # 1
Marianne Stanicheva as Uniform Cop # 2
Vasil Boyanski as Cop in Tunnel
Nikolai Iliev as Greenfield
Harry Anichkin as Homeless Man
Borislav Iliev as Hospital Security Guard # 1
Velizar Peev as Hospital Security Guard # 2
Yulian Vergov as Swat Member
Velizar Binev as Rescue Worker
Franklin A. Vallette as Prison Guard # 1
Atanas Srebrev as Prison Guard # 2
Svilena Kidess as Tia
Antoni Argirov as Young Thug
Although set in Baltimore, Maryland, Mansquito was filmed in Bulgaria.
The film has received mixed to negative reception from critics.
Dread Central awarded the film a score of 3 out of 5. Noting the film's shortcomings and rudimentary plot but complimented the film's creature design, and gore effects, stating "Mansquito is a fun throwback to the b-movies of yore that’s more entertaining than it has any right to be. Perhaps it was just dumb luck or maybe the law of averages finally caught up with them but the Sci-Fi Channel finally produced a winner."