Appalled by the experimental surgery on two baboons, African-American Jess and Australian David escape with them to the bush near where their scientist parents are working. Their barely formulated idea is to return the baboons to the wild; but Papio, with four electrodes in his head, is unnaturally passive, while big scars on Upi's chest betray why she has no stamina. At first it seems too soon to abandon them; even after both are adopted by a baboon tribe (along with the humans, who are accepted more warily), it seems necessary to protect them: Upi can't keep the pace when the baboons move on. Meanwhile, step by inexorable step, the young people become outlaws, stealing food from an African village and challenging the white hunter sent to find them--and to cruelly attack the baboons. In the end, battling the hunter, David and Jess lose sight of their purpose and unwittingly cause the destruction of the baboons. This Australian author (most notably, Baily's Bones, 1989) can be relied on for suspense--and for raising moral concerns in imaginatively provocative settings. The chief issue here is not so much animal rights as how a reasonable defense can degenerate into maintaining an untenable position at all costs. Meanwhile, some of the premises strain credulity, especially the ease with which the kids irrational--and then, in an epilogue, normal again. Still, a thought-provoking thriller with a respectable grounding in natural history and human nature.