Tim Matheson, star of National Lampoon’s Animal House and The West Wing

(and the voice of Jonny Quest in his teens!), returns for the fourth season of

the small-town drama Virgin River (July 20 on Netflix). AsDr. Vernon Mullins, Matheson, 74,

deals with his newly discovered grandson, a new doctor at his clinic, the pregnancy of Mel (Alexandra Breckenridge) and the effects of a brain injury on Hope (Annette O’Toole).

How do you explain the enormous popularity of Virgin River?

At the center of everything is Alexandra Breckenridge as Melinda; she’s the heart of the show. I think Virgin River is one of those places where everyone thinks, If I go to that small town, it’s going to be great, and then you find out not so much.

What are Doc’s biggest challenges now?

It’s Hope’s health and dealing with this grandson who’s come into his life and opened feelings about this woman who was a girlfriend for a minute, and a son he probably had who passed away and he never got to meet. So it’s unlocked a lot of old wounds.

Doc Mullins has a lot going on this season.

It was a great season, I thought. There was so much going on and so many different elements to his life and to his career. It was like, “Wow!”

Doc and Hope had just been reunited when Hope went on a trip to take care of an aunt and she had this serious car accident. What’s it like when he realized she may never be the same after he waited so long to be reunited with her?

It’s very traumatic. It’s worse for her and kind of disappointing because just when they thought they would get it back together, she may never recover. We don’t know. She does show sparks of her old self and, as we all know when we’re treating somebody who is ill—my mother had dementia—they get a little ornery. Brain injury is not dissimilar to dementia, so the only question, the real hope and prayer is that she recovers and returns to who she was.

Is it harder for him because he is a doctor, and he knows the reality of it, than it would be for someone not in the medical profession?

I’m always trying to stay in character when I’m working, and from the reading I’ve done about country doctors and why they’re drawn to that lifestyle rather than work at a big hospital, I think it is harder knowing. He doesn’t want to tell her everything and he doesn’t want to get into technical explanations of this and that, but he’s very aware of the odds and her strength. Anything he can do to help her recover is vital to him. Balancing that with his work and with his young grandson coming to see him, it’s a delicate balance.

How is he as a grandfather considering he was never a father?

I think that’s the crux. He’s exploring that relationship tentatively at first but embracing it more and more. It’s charming and it’s fun and it’s waking up a part of him that he has never ever connected with, which is your progeny, your offspring.

When Mel first showed up in his office, Doc was very brusque, to put it mildly. He seems to really have mellowed and they seem to have a really nice relationship now. How do you explain the change?

I think Mel proved her mettle, she proved herself in a variety of situations. She’s been extremely helpful to him and a worthy partner. She’s hard to dislike. I just adore her. That’s the daughter Doc never had. There’s a connection between them, and Alex Breckenridge, I just can’t resist her. She’s just one of the loveliest people I’ve ever met. It’s so great to work in a scene with her because it’s just so real and natural. What a pro and wonderful scene partner.