Blood hunters

In the middle of the Mexican jungle a small scientific team prepare to embark on an exploration of the world's deepest sinkhole; a naturally-formed underwater shaft that no one has ever reached the bottom of. What they are about to discover could change the world forever. Three thousand miles away, Joe McDonald's father is arrested for murder. Joe and his friend Giles are desperate to prove his innocence, but when more people are attacked in mysterious circumstances, Joe begins to suspect that a predator is on the loose. Maybe the dark shapes he has seen in the woods and canal aren't just his imagination. Could the attacks in Joe's town be linked to his dad's research at the university? Could Dad's colleague have brought something back with him from the expedition in Mexico? Suddenly the search for justice becomes a desperate fight for survival...