Lauro kicks Iditarod training into high gear with a 300-mile run on the Denali Highway; Bret and Ivy go from checking traps to hunting moose, and take the opportunity to bring down a large bull; Mike responds to a bridge washout by going on the offensive against destructive beavers; Tom helps Paul with running his trapline and skinning his catch; Jake tracks a killer lion, but his hounds turn up a different kind of cat.