Genetic engineers Clive Nicoli and Elsa Kast rise to prominence in the field of biotechnology by successfully combining various animal DNA to craft astonishing hybrid creatures. Eager to push the boundaries of their work, they aim to incorporate human DNA into their experiments, aspiring to create a hybrid that could revolutionize both science and medicine. However, the pharmaceutical company financing their research, N.E.R.D. (Nucleic Exchange Research & Development), strictly prohibits them from using human DNA, insisting that their efforts should be redirected toward the extraction of specific proteins from the existing hybrids they have already created.
Frustrated with this limitation and unwilling to waste five to ten years on what they deem tedious research, Clive and Elsa take matters into their own hands, conducting secret experiments that blend human DNA with that of other animals. Despite their initial disagreements about bringing their hybrid to maturity, Elsa's determination persuades Clive to go along with her plan, leading them to create a remarkable creature named Dren (which is "nerd" spelled backward). Dren rapidly grows and evolves in ways that astonish her creators, leading them to relocate her to a farm that belonged to Elsa’s late mother as their lab becomes increasingly crowded and dangers of discovery loom.
Their troubles escalate when one of the original hybrid animals they created, originally a female, unexpectedly transitions to male, triggering a catastrophic incident during a shareholder meeting. This shocking event, in which two hybrids, previously in love, turn on each other as rivals, causes chaos among the audience of investors. Following this debacle, N.E.R.D. finds itself on the brink of collapse unless a profitable discovery can be made.
As Clive and Elsa's focus shifts toward Dren, her transformation takes a bizarre turn; she becomes both amphibious and omnivorous, developing a toxic sting and retractable wings. Initially, Elsa forms a close maternal bond with Dren, but her affection wanes when Dren displays violent tendencies by killing her pet cat and turning on Elsa herself. In a desperate attempt to salvage their research, Elsa removes Dren's stinger, successfully isolating a sought-after protein from it.
The situation takes a dark turn when Clive, drawn to Dren, becomes involved with her sexually, much to Elsa's horror. During a heated confrontation, Clive discovers that Elsa had contributed her own DNA to Dren’s creation, leading to a fractious argument about trust and loyalty. They decide to return to the farm to address the escalating situation with Dren, only to find her body submerged in a water tank, appearing lifeless.
After burying Dren by the farmhouse, they are confronted by their company’s boss, who suspects their experiment involved human DNA due to the protein they synthesized. When Elsa defiantly suggests the boss can exhume Dren’s body for evidence, the unexpected happens. Dren resurfaces, having survived in a comatose state, and undergoes a shocking transformation into a male. In a fit of rage, Dren attacks, killing their boss and Clive’s brother, before dragging Clive into a frozen pond. Although Elsa manages to save Clive, Dren subsequently assaults her. In a tragic climax, Clive intervenes and confronts Dren, but the battle costs him his life after Dren delivers a poisonous sting. Ultimately, Elsa seizes control of the situation and defeats Dren by smashing its head with a rock.
In the aftermath of these harrowing events, Elsa finds herself in a corporate office, where she is offered a substantial sum to maintain silence and take the experiments to a new level. As she stands up, the revelation hits that she is pregnant with Dren's child, leading to an ambiguous and unsettling conclusion to their groundbreaking yet disastrous venture.
