Grant has plunged with his trademark recklessness, wit, and curiosity into East Africa. Setting out to make the first descent of an unexplored river in Tanzania, he gets waylaid in Zanzibar by thieves, whores, and a charismatic former golf pro before crossing the Indian Ocean in a rickety cargo boat. And then the real adventure begins. Known to local tribes as “the river of bad spirits,” the Malagarasi River is a daunting adversary even with a...