Steven Turnbull (this is an alias, not his real name) is a devoted hunter. He loves nothing better than stalking elk in his home town of Crandall, Wyoming, on the edge of Yellowstone Park. But elk numbers have dwindled in recent years. Yellowstone experts blame drought, but Turnbull believe wolves, reintroduced to the park in the mid-1990s, are the real culprit. He has signed up for the first local permit to hunt wolves, a concession granted by authorities due to their growing numbers. He is allowed to bag one more this season. After carefully stalking his prey through the snowy landscape, he lines up a pair in his sights: a large, black male and his gray mate. Turnbull pauses with his finger on the trigger. He has time to choose which animal to kill.

It is December 2009. Rick McIntyre watches three wolves bring down an elk and feast on the huge beast. Rick works at Yellowstone Park and is devoted to its wolves. In fact, this is his 3,467th consecutive day spent scouring the park for them. Researchers have attached transmitters to at least one animal in each of the park’s packs (firing tranquilizer darts from helicopters to sedate them first).