At the time that Niels’s and Frank’s destinies were joined in a University of Arizona laboratory, neither of them could have known that their alliance would take them all the way to Mozambique. Niels, a Danish zoologist specializing in animal behavior, studying with support from an intercollegiate scheme, was looking into ways of training miniature dogs to sniff out antipersonnel mines. Progress was scant. According to the computer simulations of the problem, the dogs always exploded. Too heavy. Frank, a DHL deliveryman at the time, was the one bringing items to the lab. Their relationship was limited to the signing of Niels’s signature on Frank’s delivery sheets. Until one day Frank said to Niels, I’ve got a way to solve your problem, it’s rats you need, not dogs, come over to my place and I’ll show you. Niels made the near-150-mile trip to Nevada, where Frank lived with his wife and three children in a robust, well-put-together wooden house, complete with a lawn. He was taken down to the basement, and there witnessed the rat spectacular Frank had assembled for his family’s entertainment. Joined together by long enough pieces of string, and being made to pass through all manner of balance tests, they never pressed down more than was safe on any of the levers, and could smell perfectly the decoy: gunpowder from a cartridge. They’re ideal, he said. Cheap, easy to come by, once they’ve got a scent they just won’t give up, plus they weigh under 1.2 kilos—which, and correct me if I’m wrong, but I read that’s the minimum weight to set off one of those gizmos of yours? From then on they worked so closely together that Niels arranged for Frank to be given a role as an assistant at the university. Now they’re in Mozambique. The second the sun comes up they’re out there with their 15 Gambian rats, which make their way frenetically out into the prairie lands attached to pieces of 50-foot-long string; when they pick up the scent they start squeaking, and once they’ve found the supposed spot where the mine is, they stop by it, sit down, and settle down. One day a letter was wrongly delivered to their improvised field tent and Frank, who to this day hasn’t recovered from the tic of needing to deliver items as quickly as possible, decided to redirect it himself. Seeing as it wasn’t far, he decided to walk, and Niels said he ought to take a couple of rats along as a safety system. Not long after he set out, the animals became extremely unsettled and began to emit the squeak: mine. They tugged and tugged and wouldn’t stop until they reached the foot of a tree, and when they settled again, they each stopped and cast their snouts upward. From the branches of the tree, held there by lianas of some kind, hung a multitude of bones belonging to an animal that was never identified.