As the summer of his sophomore year approaches, Little Hawk worries about returning to New Mexico to face a bully who has taunted him for the past several years. His anxiety soon turns to anticipation when he discovers the mythological animal known as El Chupacabra, rumored to have hunted livestock on ranches near the reservation, in years past, has returned and is once again killing cattle. His excitement is increased when Seamus's grandfather, and Jenny's parents allow them to accompany him home for summer break, and the kids make plans to prove the creature's existence.
Upon arriving in New Mexico, the trio's enthusiasm is short-lived; for a reporter covering the story of the livestock deaths is killed in a similar fashion... and her death is blamed on the creature. When the kids set out to track down El Chupacabra, they soon discover not all is as it appears.
Can David and his friends find the reporter's true killer, and clear El Chupacabra of the crime before the once mythical creature is hunted to extinction?