A young cowboy, Caleb, living in a small Oklahoma town, meets an attractive drifter named Mae one night. Unbeknownst to Caleb, Mae is a vampire. After spending the night together, Mae bites Caleb, initiating his transformation into a vampire. As the sun rises, Caleb struggles to return home but starts to smoke and burn from the exposure. At the last moment, he is abducted by Mae and her nomadic vampire family—a ruthless pack led by the intimidating Jesse, the tough Diamondback, the psychotic Severen, and the childlike Homer. They inform Caleb that he must learn to kill in order to survive, setting the stage for his struggle with his new existence.

Caleb grapples with the moral implications of his forced new lifestyle, demonstrating a reluctance to kill for sustenance. His refusal puts him at odds with the vampire group as they move from town to town leaving a bloody trail in their wake. Meanwhile, Caleb's farmer father, Loy, and younger sister, Sarah, begin searching for him, culminating in a collision between Caleb's human past and his terrifying present. As he grows closer to Mae and learns more about his vampire brethren, Caleb must choose between embracing his transformation or holding on to his humanity.