The episode begins by flashing back to Fitz and Simmons making dinner plans in the Season 2 finale, 6 months ago in-universe. Simmons is consumed by the monolith and spit out on the dusty blue planet. She tries to go back through the portal, but it closes in the ground. She tries to use her phone and realizes she has no idea where she is. Simmons climbs a ridge and look up into the sky to see an alien planet and moon.
Six hours later, Simmons is trying to keep her cool. She recites S.H.I.E.L.D. procedure for moments like this and records her experience on the planet so far: air breathable, gravity a bit strong, looks like it could support life, but there’s no signs of any.
Thirteen hours in, she looks at a photo of Fitz on her phone, tells it goodnight, and sleeps. She wakes up at hour 22 and it is still night. 71 hours in and there’s still no sun. Simmons is beginning to break down. She wants to go home.
Simmons decides to go exploring, looking for water. She uses rocks to form an arrow pointing in the direction she went off in, in case anyone else comes through. 80 hours in and she’s talking out loud, pretending Fitz is there. At 90 hours, she’s climbing up a ridge, only to find a massive sandstorm heading in her direction. At 101 hours, she wakes up covered in sand. She finds a pool of water and drinks.
109 hours. She’s floating in the pool of water. Some sort of tentacle pulls her down. She fights her way back to the shore and chops off the end of the tentacle. At 111 hours, she’s finally convinced herself to eat it.
Three weeks in, she makes a simple weapon and uses herself as bate to lure out the tentacle again. It pulls her down beneath the water. After a moment, she reappears, a segment of the tentacle in hand for dinner. Simmons gets a fire going is this time she cooks the monster-planet’s tentacle. She continues recording her experiences. She says she needs Fitz to read her mind, to know she’s alive and to come and get her. She knows Fitz won’t give up.
One month in. She is leaving another message when she hears a noise coming from an outcropping of wood plant. She grabs her weapon and goes to investigate. She falls through a hole, and someone covers up the opening.
761 hours. She wakes up in a wooden cage. There are bowls of food and water. The other person appears, and Simmons cowers. 783 hours. The person returns, and is almost surprised Simmons is still there. He walks away. 824 hours. Simmons is doing pull ups in her cage as the other person approaches with a weapon in hand. Simmons introduces herself. She says she can help him if he lets her out. The man prods her back and leaves more food. She believes the man is fattening her up to eat. 851 hours. Simmons feigns sickness to lure the man into her cage, then she hits him with her bowl. She climbs out of the cavern and runs. The man chases after. She cuts her leg on some rock. The man catches up with her. The man begins patching up her wound. He says “it” smells blood. He hears a sound and says “it” is coming. He takes Simmons and runs to his hatch.
They go underground just as another sandstorm blows over. Simmons asks what he thinks is out there. He says “death.” Simmons believes it’s the nature of the planet, but the man believes some entity or being is causing the fluctuations on the planet. He believes the whole planet is evil. Simmons speaks of planets having definable rules. The man says this planet doesn’t have rules, only moods. The man has a first aid kit and gives it to Simmons to sew up her leg. The man explains that he doubted she was real. His name is Will. He says Simmons is the first person he’s seen in a long time. He’s lost track of how long he’s been there. She tells him the year is 2015. The man goes into another room. Simmons follows and finds NASA astronaut equipment. It looks dated. Will tells her he came here in 2001.
Simmons finds a map of the area. There’s an area marked “no fly zone.” He says only bad things happen there. Simmons notices light coming through a crack in a wall. Will says it’s a luminescent substrata that keeps everything warm.
Will explains that NASA sent him through with a team, intending for them to return within a year. He volunteered for the mission, knowing it could be a one-way trip. He doesn’t know how NASA knew there would be a planet on the other side. The rest of the team were scientists. He was there to keep everything under control. He says the thing outside got into the heads of the others. One threw himself off a cliff, another set himself on fire. The last took an axe and destroyed the gear, then attacked Will. Will was forced to kill him to stay alive. He says he’s survived through luck, avoiding the creature, and outsmarting it. Simmons tells him there’s a rational explanation for what happened. Will gets angry, says the only other explanation is that he went mad.
Simmons apologizes and says they should start over if they’re going tow work together to get home. Will says there’s no hope of getting home. Simmons says they’ll work with that dynamic.
1490 hours in. Will and Simmons enjoy a “meal” and discuss the things they miss. She show him a video of her S.H.I.E.L.D. team celebrating her birthday. After an awkward moment, Simmons turns in for the night. She says goodnight to Fitz again and, for the first time, to Will (to herself).
3010 hours. Simmons is frustrated she hasn’t figure out how to get home yet. She wants to go to the no fly zone, but Will says she can’t. He says its where they all went before they went mad.
Simmons goes outside and forages for some food to make Will dinner. She comes across the sword and items belonging to the man from the 18th century who went through the monolith. She looks up at the stars and says “that’s the answer” just as a sandstorm knock her over. She lands on top of a half-buried skeleton and sees a cloaked figure walking through the storm. She takes cover behind an outcropping and covers her cut with sand (as seen in the season premiere). She runs back to Will’s cavern.
She tells Will that he was right about the other creature. She tells him that the no fly zone is a mass graveyard that proves people have been coming through the monolith for centuries. Will knows, he just didn’t tell her. Simmons says it’s as if people are being sacrificed. Simmons pulls out a sextent and says she knows how to get them home.
Simmons has figured out that the portal is in a fixed position, but the planet continues rotating. Using the time and date that she and Will arrived, they can figure out the rate of rotation and where the portal will be. She suggests using the remaining battery in her phone to power one of NASA’s computers. She goes outside and says one last goodbye to fits – “I’ll see you soon” – and she and Will go to work.
They get NASA’s computer up and running again and use it to gather data before it finally dies. She determines that in 18 days the portal will open in the “no fly zone.”
Simmons and Will prepare for their journey outside. She explains that the moon’s pull is what opens the portal. In case the portal closes too quickly for them to get through, she’s prepared a message in a bottle with all the information Fitz will need to find them. Will shows her a grappling device he’s put together to help the get across a 30-meter wide canyon to get where they need to go.
3575 hours. They make their journey. Will says the geologist that came with them believed this planet was a paradise once. He thinks the other creature consumed the world, making it what it is now. Simmons asks if he thinks they’ll run into the creature. Will says he’s ready. He has a gun with one bullet in it, his ticket “out” if things got too bad.
They arrive at the canyon and find its closer to 100 meters wide than 30. Will says “it” doesn’t want them to leave. They see the portal open on the other side. Will ties the message in the bottle to his device and fires it at the portal. The portal closes before the bottle makes it through.
Once they’ve returned to their cavern home, Simmons gives up hope. Will says this is their home now. Simmons says this isn’t their home, its hell, and flips a table. She says Will was right, that there’s no hope. Will says that’s what he used to think until Simmons showed up. They kiss.
4720 hours. Simmons and Will, now more affectionate, prepare to go outside. They’re awaiting a brief appearance by the sun. Will pulls out some wine he took from the no fly zone graveyard and pours it for them both. They drink. It tastes horrible. Simmons says she thinks her dad would have liked Will, that sometimes he reminds her…and then cuts off when she sees Fitz’s flare.
Will and Simmons both run towards the flare. It’s just over a ridge up ahead, but a storm picks up. Will tells her to go and she loses sight of him. She sees an astronaut and thinks its NASA come to rescue them. Will tells her to run, that it’s not what she thinks. Will stays to hold the creature off. She hears a gunshot, and then Fitz’s voice calling out to her. She calls back, but waits for Will. She finally runs towards Fitz’s voice and is rescued.
Present time, Simmons finishes telling Fitz her story. Fitz is silent, and simply stands up and leaves. Simmons follows him to the lab. He pulls up data on a computer. He tell her they’re going to get him back. Simmons cries.
Will stands in the sunlight, gun in hand. He throws it on the ground. The sunlight passes, and he walks off.