When bodies wash up on the beach, is man or animal the culprit? It'll take everything forensic specialist Alexa Glock has to seek out the truth. Because lips may lie, but teeth never do.

At first, Alexa Glock's initial case as a traveling forensic investigator seems straightforward --- her expertise in teeth helps her identify the skeletal remains of a hunter found on the remote Stewart Island in New Zealand. But when she realizes the bullet lodged in his skull was not self-inflicted, and then a second, shark-ravaged body washes up on Ringaringa Beach, it's clear that something dangerous is lurking in the beautiful waters surrounding the island.

The disturbing sight seems to confirm what locals have hashed out in the pub: shark cage-diving, lucrative for owners and popular with tourists, has changed the great white sharks' behavior, turning them into man-eaters. Tensions between cagers and locals mount as Alexa --- christened the "shark lady" --- dives into the harrowing case. While measuring bite patterns, she makes a shocking discovery that just might lead her to who --- or what --- is behind both deaths.

Alexa Glock, an expert in teeth and bones, finds herself playing shark detective in the newest book of Sara E. Johnson's acclaimed forensic mysteries. But she'll soon learn that there are dark things lurking beneath the water, something far worse than a natural-born predator.