Gus' expedition with Dr. Singh leads to several shocking discoveries. Big Man and Aimee seek refuge and reinforcements. Becky connects with a new friend.

After an eventful, obstacle-strewn journey to find a safe haven, Gus learns more about his origins and how far Birdie was willing to go to protect him.

As polar night looms, Gus and his crew arrive at the outpost — but they're not alone. To find Birdie and the cave, they must brave several obstacles.