The Story Behind 'Magnificent' Meryl Streep's Show-Saving 'Only Murders' Duet with Ashley Park (Exclusive)

Warning: This post contains spoilers for season 3, episode 3, of Hulu's Only Murders in the Building.

Meryl Streep is known for infusing every one of her performances with emotion, and a duet with costar Ashley Park on Tuesday’s episode of Only Murders in the Building was no exception.

On the latest episode of the Hulu series, the two actresses teamed up for "Look for the Light," a mellifluous tune written by Grammy Award-winning artist Sara Bareilles in collaboration with songwriter-producers Benj Pasek and Justin Paul.

"As she knows, we are generally always looking for any reason whatsoever to work with Sara Bareilles, and this really felt like the perfect opportunity to do so," the Oscar- and Tony-winning composers tell PEOPLE exclusively. "Writing a song together, for Meryl Streep, was beyond any of our wildest dreams. It was the honor of a lifetime to watch a legend, who is both magnificent and humble, at work."

Bareilles told The New York Times last week that she relished the chance to "tailor" the song to Streep's "strengths There was so much tenderness in [Meryl’s]  vulnerability. She let that speak through her singing.”

Pasek and Paul agree. "Her performance in this number is equal parts emotional, tender, vulnerable and filled with her signature quiet strength," they tell PEOPLE. "It's incredibly unoriginal but nonetheless very true to say that when the opportunity to work with Meryl comes along, you just jump."

Bareilles also told PEOPLE in a statement that the "invitation" to join such a "joyful and undeniable" collaboration was a no-brainer.

“I am such a fan of the Only Murders and of Pasek & Paul, so the idea of writing together for the first time, especially to offer something to someone like Meryl Streep truly felt like a dream," she said.

She said of working with the actresses, "Meryl was gentle and focused, and I loved her musicality and her willingness to share her process. Ashley Park’s glorious counter melody was added later, and I got goosebumps the first time I heard it. It truly couldn’t have been a more seamless experience- how lucky am I to be a part of it!”

In Tuesday's episode of OMITB, Broadway director Oliver Putnam (Martin Short) made a last-ditch effort to save his foundering new play by transforming it into the song-and-dance spectacle renamed Death Rattle Dazzle.

After Oliver tinkered on the melody of "Look for the Light" throughout the episode, the song literally took center stage at the end of the hour when unproven star-in-the-making Loretta (Streep) stepped up at a reading to perform it in full for the first time. The moving performance signaled a turning point when cast, crew and investors finally agreed the show might actually have a chance at success.

Adding to the magnetic moment, ingenue Kimber (Park) joined in with Loretta toward the end of the song, their voices blending seamlessly. But the beauty was belied by a more sinister undercurrent as Oliver's podcasting partner Mabel (Selena Gomez) and cinematographer Tobert (Jesse Williams) uncovered a seemingly crucial piece of evidence in this season's murder mystery that led them to suspect Kimber might, in fact, be behind the death of the show's leading man Ben (Paul Rudd).

It was quite literally a grab-your-hanky moment, not only because of the sob-inspiring song, but also because the investigation led by Mabel, Oliver and Charles-Haden Savage (Steve Martin) may hinge on the fact that a handkerchief Ben was holding when his body was discovered might have been his dying attempt to provide a clue to his murderer's identity. As it happened, Kimber was the only cast member who was missing her handkerchief as this week's installment wrapped up.

"Look for the Light" is just one musical number that will feature in season 3A Strange Loop's Michael R. Jackson will provide new material, as will Hairspray visionaries Marc Shaiman & Scott Wittman in addition to Pasek and Paul, who are known for their work on Dear Evan Hansen, The Greatest Showman and La La Land.

Back in January, OMITB star Steve Martin revealed that Streep would be joining the ranks with Rudd for season three with a picture shared on Twitter. 

The black-and-white photo was a selfie that included Martin, Streep, Rudd, Short and Gomez.

“The filming of Season 3 of Only Murders in the Building has begun!” Martin, 77, captioned the post at the time. “A cast to dream of.”

Gomez, 31, also joined in the excitement shortly after Martin’s announcement by posting a video to her Instagram showing off the stars as they welcomed Rudd, 54, and Streep, 74, to set.

"Hey guys, we're on set! What are we shooting? Season 3! The gang is back!" Gomez said as she panned the camera to her Martin and Short, 73. "Yay! Could this honestly get any better? Oh wait!"

She then turned the camera to Rudd and ultimately to Streep, excitedly revealing the full crew working on the third season.

Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.

“Look for the Light” is now available to stream on Apple and Spotify. New episodes of Only Murders in the Building  drop Tuesdays on Hulu.