SERU (Sensory Enhancement Research Unit) is a secret facility devoted to enhancing military capabilities. Among its genetically mutated experiments are extremely clever and dangerous rats; a killer guard dog; and Dusk, a human girl who possesses hawk genes, the result of a failed attempt to create perfect night vision. When a fire erupts and destroys SERU, all of the specimens escape to a nearby deserted town. The military pulls out to cover its illegal operations, and the escapees live there under a strict, and very tense, state of peace. Two years later, a boy enters the village and disrupts that truce. It is then that Dusk has to take sides: is she human or animal?