9-1-1: Lone Star actors tease 'really good' Tarlos episode, and an exclusive preview of Owen's 'creepy' new pet

9-1-1: Lone Star's Carlos and T.K. have been through a lot this season: A tense breakup, T.K.'s coma, moving in together again, the death of TK's mom, getting drugged by Owen's stalker...and that's just this season!

Monday's episode of the Fox drama will pick up in the wake of all the chaos brought on by Owen's (Rob Lowe) stalker, Sadie (Julie Benz, who first appeared as his neighbor in the season 3 premiere).

As seen in the exclusive preview clip below, Owen has moved on from the trauma quickly, focusing on welcoming in Horacio, the "creepy" hairless cat his new girlfriend Catherine (Amy Acker) raised with her ex boyfriend. But T.K. (Ronen Rubinstein) and Carlos (Rafael L. Silva) are not as lucky: In drugging T.K., Sadie put the first responder back at Day 1 of his sobriety, something the couple — known to fans as "Tarlos" — now have to grapple with.

"Through no fault of his own, T.K. relapsed. And so, we started off Monday's episode with T.K. coming back from a meeting. And Carlos tries to be there for him in the best way possible," Silva tells EW. "But this experience is very specific to T.K., and this is something that Carlos has never experienced. So, we're going to see Carlos try to be there for T.K. in the way that T.K. needs it, not the way that Carlos deems it important."

Monday's episode will also introduce T.K.'s AA sponsor, "which makes for a really, really, really intriguing storyline, and that's definitely going to affect Carlos," says Rubinstein. "So, we'll see how the two of them are able to navigate that."

"We're also going to see how T.K. is handling losing his mom," Rubinstein continues. "It's something that I don't think he will ever get over, and I'm quite relieved that we're still showing that in the show — because in the past couple seasons, we've brushed past major traumas in an episode or two, so I'm glad that we're still continuing that."

The actors both feel Monday's episode contains some of their "favorite scenes" of season 3, with Rubinstein adding, "I've been teasing this episode a lot. And I think the fans know when I tease an episode for multiple weeks, they know it's going to be really good — and we haven't disappointed them yet."

A new episode of 9-1-1: Lone Star airs Monday at 9 p.m. ET on Fox.

Sign up for Entertainment Weekly's free daily newsletter to get breaking TV news, exclusive first looks, recaps, reviews, interviews with your favorite stars, and more.

Related content:

• How (and why) 9-1-1: Lone Star killed off Lisa Edelstein's character
• Rob Lowe and John Owen Lowe to bring father-son dynamic to new comedy series
• Watch Rob Lowe describe The West Wing while on a date with a politician on 9-1-1: Lone Star