As the final two episodes of Severance Season 2 approach, one question looms larger than any other: What in the world is Cold Harbor?

It's a mystery that's haunted us right from the Season 2 premiere, but since then, Severance has provided viewers with some major reveals that have better clued us into what these two words really mean.

From Mark's (Adam Scott) MDR file to Lumon's testing floor rooms, here's everything we know about Cold Harbor so far.

Cold Harbor is the name of Mark's current MDR file — and only he can complete it.

The Cold Harbor file in "Severance."
Credit: Apple TV+

Let's start with the basics. As we learned back in Season 2, episode 1, Cold Harbor is the name of the file Mark is currently refining for Lumon. At the start of the season, he's 68 percent of the way through. By episode 7, he's 96 percent done with the file. However, as he recovers from his reintegration-induced seizure, there's no telling how quickly he'll be able to finish Cold Harbor.

In the first two episodes of Season 2, Severance makes it clear that Mark — and only Mark — finishing Cold Harbor is Lumon's priority. That's why they hired him back after the Overtime Contingency fiasco that concluded Season 1. That's why they were so quick to give into his demands that his original team return to the severed floor.

Mark is such a key part of the Cold Harbor project because of his deep connection with Gemma (Dichen Lachman), on whom Lumon is experimenting as a result of MDR's refining. Speaking of…

Cold Harbor is one of the rooms Gemma goes through on the testing floor.

Dichen Lachman and Sandra Bernhard in "Severance."
Credit: Apple TV+

Just like with MDR's other files — including Allentown, Dranesville, and Siena — Cold Harbor is the name of one of the many rooms that Gemma goes through daily on Lumon's testing floor.

As seen in episode 7, each room houses a different Severed identity of Gemma's, as well as an unpleasant situation, like a turbulent flight or a trip to the dentist. For each Innie, these experiences are their entire life, a nonstop loop of torture.

After Gemma endures the rooms, the sinister Dr. Mauer (Robbie Benson) prods her about whether she can recall anything that happened in them, or whether any emotions from her Innies' time in the rooms bled through to her. The answer is no, but that doesn't stop Gemma retaining physical pain — like aching teeth or a cramped hand — from some rooms.

This line of questioning proves that Lumon is testing the severance barrier to see what, if anything, bleeds through from these terrible experiences. Based on that, it seems like Lumon's endgame is creating a way to sever all painful experiences, which they can then sell to the masses. As Dr. Mauer tells Gemma when she asks about seeing Mark, "Mark will benefit from the world you're siring. Kier will take away all his pain just as Kier has taken away yours."

Of all the rooms on the testing floor, there's only one that Gemma hasn't been in: Cold Harbor. Given that Mark has to be the one working on it, it's likely that this room presents the biggest emotional challenge yet. If the severance barrier can hold while Gemma is undergoing emotional turmoil that Mark somehow created or controlled, then Lumon knows its goal is complete.

What is in the Cold Harbor room?

Dichen Lachman in "Severance."
Credit: AppleTV+

Since we haven't been in the Cold Harbor room yet, we can't know for certain. However, fan theories on Reddit speculate that the room will present Gemma's Cold Harbor Innie with the death of a loved one or a reminder of her miscarriage, therefore testing whether Gemma can forget devastating grief.

What happens to Gemma after Mark finishes Cold Harbor?

Dichen Lachman in "Severance."
Credit: AppleTV+

We obviously have a lot of questions about what Cold Harbor will turn out to be, but another nagging issue is what Lumon will do with Gemma once it's finally finished its big project.

When she asks Dr. Mauer outright what will happen after she goes through Cold Harbor, he tells her, "You will see the world again, and the world will see you."

In theory, then, Gemma will be going back out into the world. But will it be as herself? As Ms. Casey? As one of her other various Innies? After all, there's no way Lumon would willingly let someone they've kidnapped back out into the world unless they can control the narrative.

Another less-than-promising hint at Gemma's future comes during an episode 7 discussion between Dr. Mauer and Mr. Drummond (Ólafur Darri Ólafsson), when Mr. Drummond says, "When [Mark] is done, you're gonna have to say goodbye to her."

But does that mean "goodbye" as in Gemma is leaving the hellhole of the testing floor for good? Or "goodbye" as in a permanent farewell to Gemma? When it comes to Lumon doublespeak, we should always skew more sinister — and it seems like no matter what Cold Harbor brings, Gemma is still very much in danger.

Severance Season 2 is now streaming on AppleTV+, with a new episode every Friday.

Vicky