The Good Doctor star Freddie Highmore says the finale sets up a 'big journey' for Shaun

The Good Doctor star Freddie Highmore believes season 4's finale will as much of a game-changer as last year's ender, at least on the relationship front.

"I think it's pretty big for everyone," the actor, who plays Dr. Shaun Murphy, tells EW. "Starting with Morgan [Fiona Gubelmann] and Park [Will Yun Lee] figuring out their friendship-relationship and what they want that to be. Or Lim [Christian Chang] and Mateo [Osvaldo Benavides], their budding friendship or whatever one might want to call it. And Claire [Antonia Thomas], too. I think she's been incredibly touched by working in Guatemala and the experiences she's had there, perhaps more than any of the other doctors. It's a big episode for her, too."

Titled "Vamos," the hour is an especially pivotal one for Shaun and Lea (Paige Spara), who are still dealing with the aftermath of their miscarriage. The first part of the finale ended with Lea telling Shaun that she's seriously considering moving back in with her parents because she's still struggling with that loss.

"For Shaun and Lea, it's kind of as big as it can get in terms of a relationship for the two of them in this last episode," says Highmore. "What they've been through are the sorts of things can that can make or break a relationship, and that's what we'll look at."

From Highmore's perspective, Shaun is also having a hard time emotionally, too. "I think Shaun still has to deal with some of that," he says. "But I think that builds an understandable pressure to try and be there for Lea and to put himself second because he knows, as sort of a conscious thought that he's having, he needs to try and support her and that she has it worse than he does. I think that's what he's grappling with in that last scene, or that line that he gives, 'I'm sorry you're sad.' There's not really anything else he can say. He doesn't know how to help. He's kind of a little bit lost, but he certainly wants to be there for her."

On top of the relationship drama, Shaun will also have his hands full on the medical front. In the last episode, Shaun and the other doctors picked the 10 surgeries they would perform at the Guatemalan clinic. Unfortunately, the clinic loses power in the finale while Shaun is performing a risky surgery.

"Certainly Shaun is accustomed to ways of doing things. So when the electricity cuts out early on in this episode and they're left to their own devices, in some ways you would imagine that would be incredibly troubling for Shaun. But also, we'll get to see Shaun at his best, which is when he is able to think differently and able to view a medical solution that others can't quite see," says the actor-producer.

However things shake out, we know the finale will have ramifications for Shaun's life moving forward. Says Highmore: "What we set ourselves up at the end of the season for season 5 will be another big journey for Shaun to go on."

The Good Doctor airs Mondays at 10 p.m. on ABC.

Related content:

• See Shaun reveal his feelings about Lea's pregnancy in The Good Doctor sneak peek
• The Good Doctor clip: Lim opens up about losing a patient in the pandemic
• The Good Doctor boss on [SPOILER]'s emotional return