Ever since the Season Two finale of Marvel's "Agents of S.H.I.E.L.D.", Agent Jemma Simmons has had a rough go of it. First, she was sucked up by an ancient Inhuman artifact called the Monolith. Then, she took a one-way trip to a barren alien planet with no supplies and no hope. With Fitz's help, she finally found herself Earth-side again, only to suffer from some harsh side effects thanks to her long exposure to a different atmosphere. And then, after all that -- she wants to go back?!

"Agents of SHIELD's" Elizabeth Henstridge Hints at Simmons' Season 3 Fate

"Agents of S.H.I.E.L.D." star Elizabeth Henstridge spoke with CBR News about "4,722 Hours," tonight's all-new episode of the ABC series that reveals what happened to Simmons during her six-month extraterrestrial adventure. She weighed in on what it was like to bring Simmons outside of the group, how the experience makes Simmons more like Melinda May (Ming-Na Wen), what motivates her to open up to Fitz (Iain De Caestecker) and more.

CBR News: With a few rare exceptions, "Agents of S.H.I.E.L.D." has largely been an ensemble show. What was it like for you to bring Simmons outside the group into an episode focused solely on her?

Elizabeth Henstridge: It was awesome! I love being part of an ensemble, but I was just so flattered that they were going to trust me to do an okay job and to do the story of what happened to Simmons justice. It's a testament to the bravery of the execs and all the producers. We had the best writers: Craig Titley, who was the main writer of the episode, and Jesse Bochco is a regular director on the show -- we just have such a strong team behind it. Even though it was mainly about Simmons, we still have the ensemble of all the crew. It was definitely a team effort. The rest of the cast was very supportive and very excited. I definitely felt them with me. It was a wonderful episode to film, but I was very pleased to get back with the cast. I missed them!

Simmons appears deeply, deeply affected by her extraterrestrial experience, so much so that she seems to have developed something akin to PTSD. What did you do to prepare for that?

I did a lot of research into it, both on the psychological implications but also on the physical implications: what happens when you're without sunlight for a large amount of time, how that affects your body, how that affects your system, how you can get a lot of aches and pains, bone issues -- I just started with the research, really. I didn't know the full story of what happened on the planet going into the season. I didn't know she ever wanted to go back at that point. I just knew that everyday activities [and] her sensory perspective would be different. I concentrated on the physical side of it because I didn't know the full emotional story yet. Then, when I found out what happened on the planet... that's a whole other [problem]. The conflicts between her feelings for Fitz and her feelings for other people created a whole new set of problems.

In Season Two, Simmons spent some time as an undercover agent in hostile territory. Do you think that experience helped her at all with what she faced in this episode?

Oh, definitely! I think they've all been briefed on what to do and what the protocols are if something like this happens. As she relied on that, definitely. She relies on them at the start. When it becomes apparent that she's not going to get rescued, it becomes something very different. We see her go on a journey from complete despair and then survival. That is not in any of the rulebooks she's read. That was her initiation into what it is potentially like to be a Melinda May -- Melinda would have known exactly what to do. I feel like at a point Simmons had to figure out herself.

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At the end of "Devils You Know," the last episode, Simmons finally opened up to Fitz. There was clearly a lot of inner turmoil leading up to that. Where was she emotionally when she made that decision?

They're so used to figuring out problems together, and they work best when they are FitzSimmons. I think she tried everything -- she tried to research the planet and how to get back in secret on her own at night, and then she was discovered by Bobbi. If there was any way other than asking Fitz for help, she would take it because it is such a huge ask and she would have to do a lot of explaining to him in order to elicit help, which would be very painful for both of them. She was just out of options. She knew that she needed him. That's the thing with those two; they just are better together. Even though they have been through so much apart, they always seem to need each other's help or expertise or something. That was a very difficult position. She knows she's putting him in an impossible situation, but she can't see another way.

Starring Clark Gregg, Chloe Bennet and Ming-Na Wen, "Agents of S.H.I.E.L.D." airs Tuesdays at 9 pm EST on ABC.