Last week’s “Agents of SHIELD” left three of our main characters trapped on a hellish planet with only one method of escape and an Inhuman monster lurking somewhere close by, and in Tuesday’s midseason finale, titled “Maveth,” things are going to get messy.

When we last saw our heroes — and villain — Grant Ward (Brett Dalton) was leading a Hydra team to retrieve the deadly Inhuman from the desert planet with the reluctant help of Leo Fitz (Iain De Caestecker), but both were oblivious to the fact that SHIELD director Coulson (Clark Gregg) has gone AWOL and followed them through the portal in order to seek revenge after Ward killed his short-lived flame, Rosalind (Constance Zimmer) — if he can recover from that nasty bump on the head, anyway.

Dalton hints that “something big and life-changing” happens on the other side of the portal in the winter finale, which may explain why Ward seems to have fully embraced his evil organization’s motto in the episode’s preview trailer: “In the preview, he says ‘hail Hydra,’ and I don’t think he’s ever said that, even jokingly, in the whole show up until that point,” he notes.

While Ward initially seemed skeptical about Gideon Malick’s (Powers Boothe) scheme to retrieve the creature from the other side in order to secure Hydra’s victory, Dalton notes that this week, “I think he’s open to it in a way that he hasn’t been at all in the past.”

Ever since Ward went rogue in season one, he and Fitz only seem to enter each other’s orbit under the most dire circumstances, and this week’s episode is no exception. “It’s never scenes where we have dinner together and talk about our feelings, it’s never casual interaction – there’s always some big huge thing that happens,” Dalton laughs. “So it’s not a walk in the park, but it’s so fun to play.”

Dalton is effusive in his praise of De Caestecker, who he says “brings out the best” in his performance: “I love Iain, personally, so any time we get to work together is just awesome. I have so much respect for him as an actor, too — especially this season, he’s doing just phenomenal work. So it’s an honor for me to be up there with him and I think we dance well together.”

There will undoubtedly be tension between Fitz and Ward after all the two have been through, but that’s nothing compared to what we can expect if Coulson catches up with them, since SHIELD’s director has become uncharacteristically reckless in his pursuit of his former agent. “In a way, by taking out Rosalind, I get him to react really as Ward would, I get him to really play my game,” Dalton notes of the dynamic between the pair. “It is really cool to see that, and I play dirty … Ward will do anything to get the job done. I think it’s really cool to see Coulson throw sand in my eyes too, with what he does by going off-book and getting my younger brother and doing all of that stuff [last week], so it is really exciting to see somebody so buttoned-up get so riled up. It’s like, ‘oh, I’ve woken up the beast, there’s somebody else in there – I like that. I can work with that.'”

While Dalton can’t reveal much about the events of the midseason finale before it airs, he does have one hint: “Some things happen on the other side of this portal that will have permanent, radical and huge consequences” back on our world.

Come back to Variety after the episode for more intel on the events of the episode and what we can expect when the show returns in the new year.

“Marvel’s Agents of SHIELD” airs Tuesdays at 9 p.m. on ABC.