Long feared as ferocious, the magnificent shark rarely takes a bite out of a human. Indeed, sharks have more to fear from humans than we do from them. With a booming trade in shark cartilage--touted as the latest miracle cure for countless diseases--the world's shark population is being slaughtered at an unprecedented rate.

Underwater photographer Tim Calver was drawn to biologist and leading shark researcher Dr. Sam Gruber's world-famous research lab in the Bahamas, where he is now a free-diving expert (who can hold his breath under water for five full minutes), a specialist in capturing and freeing sharks for study--and a passionate defender of these misunderstood animals.