Lupe Dávila and Javier Utierre try to solve a series of grisly murders sweeping through Puerto Rico before the killer catches up with them. When Lupe Dávila arrives in Puerto Rico for the summer, she'll be staying with her uncle, the local police chief. Javier Utierre's friends are dying in a series of grisly murders. Is it the el Cuco -- or someone human? Working together, Lupe and Javier will have to step into the shadows to see what's lurking there: murderer, or monster? -- adapted from jacket.