Logan Ribar

Family members are dropped off miles apart and must navigate the unforgiving terrain of Northern Vancouver Island to find each other; to win the $500,000 prize, the competitors must build their own shelters and forage for their own food.

As Vancouver Island is pummeled by torrential rains, the remaining teams scramble to avoid freezing floodwaters; one team attempts a massive construction project, while another must choose between betraying a family member and tapping out.

Now that most teams are reunited, they dive into the difficult task of surviving together and feeding two people; meanwhile, the final hiker faces a brutal mountain climb that could dash his hopes of ever making it to camp.

As their teammates attempt to set up camp, the hikers find that Vancouver Island's terrain is even more punishing when on the move; the island beats one pair into submission, while another grapples with a devastating accident.

A behind-the-scenes look at season four of the series, "Alone," during which seven pairs of family members are dropped off miles apart on Northern Vancouver Island; an introduction to the teams includes analysis of what it takes to make the cut.

The three remaining teams scramble for a long-term advantage; team members run themselves ragged with an elaborate shelter build; a team hazards the freezing waters of the Pacific on their own small craft.