Editor's note: The below contains spoilers for the For All Mankind Season 5 finale.

For All Mankind has wrapped up its penultimate season by dealing yet another devastating blow. With the Marsies trying to take back control of Happy Valley from the M-6 soldiers and Aleida (Coral Peña) desperately trying to reach her team on Titan, everything comes to a stunning conclusion when communication finally breaks through. Kelly (Cynthy Wu), Walt (Christopher Denham), and Elena (Kristina Klebe) have found life on Titan, but a critical mechanical issue forces the group to make a sacrifice. There's only enough oxygen for two people to walk back to their ship, and as the commander, Kelly decides to stay behind. On Happy Valley, the M-6 commanders have ordered a ceasefire, stopping the bloody attack on the Mars base. The season ends with a gut-wrenching final letter sent from Kelly to Alex (Sean Kaufman) on Titan before the story flashes forward, now set firmly in the 2020s. The final shot sees a mysterious, abandoned space shuttle come back to life with a cryptic message written on the screen in Cyrillic.