Deftly weaving the forays of two individuals, separated by a century,  into the unknown heart of Africa, Schulman’s fourth novel, her first in  11 years, tracks an engineer named Jeremy, who in 1889 accepts a  contract to supervise the construction of a bridge in British-controlled  East Africa, and female botanist Max Tombay, who travels to modern-day  Rwanda at the behest of a pharmaceutical company in search of the next  blockbuster drug. Though Max treads undaunted into gorilla territory,  the threat posed by child soldiers makes her wonder if her search is  worth it. Jeremy feels Africa’s pull in a more personal way; he’s an  outcast in his Maine town and dreads a life spent at the side of his  disapproving widowed mother. Sympathetic to her two loners while  accepting their faults, Schulman (A House Named Brazil) nudges her  characters into their fears in order to measure their reactions, but her  greatest asset is her cultural sensitivity. Finding the lonely orphan  in an armed child or the playful cat within a man-eating lion, she  yields her story’s mysteries slowly, with evident relish. Agent: Richard  Parks, the Richard Parks Agency. (Feb.)