Sinatra and Xavier confront the past, returning to the harrowing day that brought them to Paradise.

Worlds collide. Time is of the essence for Xavier. Link and his team spring into action. Sinatra puts it all on the line.

Xavier has unfinished business. Meanwhile, Sinatra meets with Link as Paradise prepares for a potential threat.

Xavier and Annie travel to Atlanta, contrasting life in this new world and the one he left behind in the bunker.

Xavier and Robinson race to find President Bradford’s murderer before it's too late.

Xavier battles the elements and other threats as he follows a broadcast to Atlanta in search of his wife, Teri.

Agent Xavier Collins is interrogated. Samantha Redmond (codename Sinatra) begins to reassure the community as she reflects on how she got to Paradise.

Isolated, Xavier seeks answers on his own and cautiously turns to Dr. Gabriela Torabi. Meanwhile, Billy and Jane feel the pressure from Robinson's investigation.

Xavier and Gary set their plan in motion. Back in Paradise, Sinatra takes action, while Gabriela follows a new lead, and Jane's past is revealed.

Sinatra wakes to discover a new paradigm in the bunker and takes steps to safeguard its biggest secret.