A horrific series of mutilated seal corpses are washed up on a remote Atlantic island, disfigured in a way never seen before, their hides torn off in a spiral. It takes ten years of investigation for experts to uncover the 'corkscrew killer'. When all potential culprits have been ruled out, the only possibility remaining is the Greenland shark but everything we know about it rules it out as a suspect. Partially blind, this twenty foot monster stays deep and is known as a sluggish, bottom dwelling scavenger - so slow-moving in fact, it's called the "sleeper shark". But as the sea ice begins to form and the seal mutilations increase, biologists are forced to re-examine their opinions about this mysterious creature and what they discover changes science forever... the Greenland shark, contrary to all existing evidence, is a stealth predator.