Sailing the Amazon with a group of botanists, 'Skeleton Detective' Gideon Oliver is on his dream vacation. But it turns nightmarish when fierce head-hunters narrowly miss killing the group leader, then a deranged passenger kills a botanist and flees. Long-past enmities and resentments-and new ones as well-might explain things. And when a fresh skeleton turns up in the river, Gideon is sure that, in this jungle full of predators, humans may be the deadliest of all.