A woman missing for seven years turns up at a hospital with strange scars on her back but can't -- or won't -- reveal where she's been.

An agonizing dilemma gives OA a new perspective on the group's plight. Homer resolves to find out what Hap's experiments are really about.

While Hap zeroes in on a new test subject in Cuba, Homer and OA work to perfect their escape plan. Scott reaches his breaking point.

After OA recounts a dramatic final night at Hap's, the others begin to see her story in a new light. The fragments of the dream click into place.

Karim visits Nina at the clinic for help finding the secret entrance to the house. Meanwhile, Hap meets a fellow traveler, and Homer goes on a date.

After a harrowing ordeal, OA and Karim find themselves locked inside a labyrinth of puzzles. Nagging doubts prompt Homer to snoop on Dr. Percy.

Karim returns to the house with reinforcements, OA tries to access Nina's memories, and Hap offers to discharge Scott -- after one last experiment.