'Castle Rock's Co-Creator on That Carly Simon Song Cameo & More About Season 2's Music

Meaghan Darwish
Spoiler Alert Hulu

[Warning: The below contains MAJOR spoilers for Season 2, Episode 1 of Castle Rock, "Let the River Run"]

Castle Rock's Misery-inspired second season has arrived on Hulu, and if you've had time to catch the premiere episode, one song may be stuck in your head.

Sharing the episode title, Carly Simon's "Let the River Run" serves as a throughway to Annie Wilke's (Lizzy Caplan) life before and after she arrives in Castle Rock — the sleepy Maine town depicted in various Stephen King works. The episode kicks off with the tune as we're introduced to Caplan's version of the iconic character.

Throughout the first few minutes of the episode, we learn she's a nurse moving from town to town, stealing anti-psychotics from the pharmacy closets and putting on a genial facade for daughter Joy (played by Elsie Fisher). The light-hearted sequence slowly grows somber when you notice Joy's enthusiasm wanes with the passage of time.

'Castle Rock's Co-Creator on Lizzy Caplan's 'Terrifying' Transformation Into Annie Wilkes

'Castle Rock's Co-Creator on Lizzy Caplan's 'Terrifying' Transformation Into Annie Wilkes

Plus, he opens up about Stephen King vet Tim Robbins' role.

The song drops off when the ladies stop at a gas station before their Castle Rock arrival, but is eventually picked back up after Annie kills Ace Merrill (Paul Sparks) with an ice cream scoop. The device works as a nice end-cap to the installment, juxtaposing Annie's happiness on the road and her coldness in Castle Rock.

We asked Castle Rock's co-creator Dustin Thomason about the song choice in a recent interview. "In the writer's room, we spend so much time thinking about it," he says of the music selection for the series. "They're singing the song in the beginning, so we had to give so much thought long before we got to post about what that song was going to be. And I had always loved that Carly Simon song," he muses.

Annie Wilkes, before and after arriving in Castle Rock (Credit: Hulu)

"There are a lot of Carly Simon songs that I love, and if you keep tuning in...  she comes back, but I think that part of what that song represented was the spirit of who we wanted this season's Annie Wilkes to be."

Who is that Annie Wilkes you may ask? "This strange, whimsical mix," Thomason elaborates. "It's a very strange song, "Let the River Run." It's odd, it's eccentric, it's emotional, and anthemic, too, so it's this mix of things and that's what I wanted Annie to be."

'Castle Rock' Cast on Season 2 Relationships & First Season Connections (VIDEO)

'Castle Rock' Cast on Season 2 Relationships & First Season Connections (VIDEO)

Lizzy Caplan, Elsie Fisher, Paul Sparks, and more of the cast preview a very different looking Season 2 of the Hulu anthology.

Despite the dark nature of the song's return at the end of the episode, there's something highly comical about watching Annie search for a location to dump Ace's body. "Cutting to that," Thomason says, "using that song at the end and coming full circle on it, obviously, at some level, I would hope that the fun of watching Annie Wilkes is that you feel like you're in on it with her."

"And then, in some ways, by starting and ending the episode with that massive song, it's going to have a different effect tonally... It's such a big choice. But it felt like, with Annie, we had to make big choices, and I think people will find those big choices all throughout the season to match who she is and this weird mix of optimism with darkness that I think is so important to the character," Thomason concludes.

If you're less aware of Simon's song from Working Girl, check out "Let the River Run" below.

Castle Rock, Season 2, New episodes streaming Wednesdays, Hulu