Miranda Hollander (Helena Mattsson) is a beautiful and smart young woman. She is a college professor and lives with her “uncle”, Tom Hollander (Ben Cross) who works in a museum; he adopted her after a car crash killed her parents. Miranda can read books just by touching them, without even needing to open them. Miranda believes that she has lived with her “uncle” ever since her parents were killed in an accident while she was a baby. After her birthday, Miranda passes out and is sent to a local hospital. Tom is notified by the police. When Miranda arrives at the hospital, she silently transforms into alien form, strips naked and seduces and kills a few people. When Tom finally arrives at the hospital the following morning, he finds bodies everywhere. Tom locates Miranda, injects her with human hormones and begins driving her to Mexico.
On the way to Mexico, Miranda wakes up, asking for the cause of her ‘illness’. Tom tells Miranda that she is the result of an experiment that combined human and alien DNA, an experiment conducted with his friend Forbes McGuire (Dominic Keating) while they were both still in college. Tom has been injecting her with human hormones since her childhood to suppress her alien DNA (thus she never entered a cocoon stage and aged like a normal human). Her parents never existed; they were just a fiction created by Tom to help build up Miranda’s “normal life”. Tom explains he and Forbes parted ways because of differences of opinion over their vision of their creation.
When they arrive in Mexico, Miranda rests in a motel room while Tom spends the day searching for Forbes. After a few incidents, Tom and Miranda locate Forbes’ current home. Forbes now lives with his recent experiment named Azura (Marlene Favela), another human and alien DNA hybrid who also serves as his assistant and lover—she is sterile to prevent offspring. Forbes supports his experiment by creating half-alien facsimiles of dead pets and relatives. Forbes checks Miranda’s condition and finds that Miranda has reached the end of her lifespan and will die in days; her changes to alien form are her body’s way of fighting back as her human form has a weaker immune system. The only way to deny death is injecting fresh human DNA into Miranda. Miranda won’t allow that to happen when she realizes it will result in the sacrifice of another human being. Again, Miranda becomes unconscious. Tom goes searching for a “donor” and is mugged by a woman in the process. Azura then incapacitates the mugger and the two bring her back to Forbes’ lab, where they succeed in extending Miranda’s life.
However, Miranda starts acting odd, joking about having sex with Azura. Tom checks her blood as she invites him to get drunk and have sex in their hotel room; he tells her to rest, believing she is delirious from the procedure. She leaves in a huff. Tom finds Forbes did a sloppy job; Miranda’s hormones are unstable, causing her alien side to become increasingly dominant. Driven by her alien sex drive, Miranda manages to seduce the innkeeper, another hybrid; however she kills him mid-process upon finding he is sterile. She goes to a bar for potential mates, seeing that a female singer in a provocative red dress is garnering a lot of attention. She sneaks backstage, intimidating the singer into giving up her dress.