What's in store for season four of HBO's Girls? "Big changes for the characters," says music supervisor Manish Raval (the show premiered Jan. 11). In addition to Lena Dunham's Hannah Horvath leaving New York for grad school, "New relationships are starting and everyone is living beyond their boundaries -- physically and emotionally." Soundtracking the transition: well-known classics -- "You'll hear Patsy Cline, Chet Baker, Charles Mingus," he says -- along with several new exclusive tracks that the series will premiere. Raval, 40, reveals three music cues.

'Girls': The Top 10 Awkward, Amazing Musical Moments

St. Vincent: A new song by Annie Clark will close out an episode, an exclusive Raval secured partly by dropping the friend card. "I said to St. Vincent's people, 'We love Annie and she and Lena are friends. Is there anything laying around?' They sent us a demo of a song called 'Teenage Talk' that she hadn't released yet and it was amazing. Lena flipped for it."

Nico Vega's 'I Believe' Stars in Trailer for 'Girls' New Season

Family of the Year: The Los Angeles indie band broke out big in 2014 with "Hero," the song that closes the film Boyhood, but one of its earliest synchs was on Girls. "It was a really short use on season one," says Raval. "Whenever we heard 'Hero' afterwards, Lena and I would wink. We were super fortunate to get a first listen to the new album." Raval licensed the very first track he heard, "Carry Me," for "a really big emotional scene that leaves us wondering where Hannah's head is at as we look toward the future of season five."

Does the 'Girls' Season 4 Trailer Make a Joke at Selena Gomez's Expense?

Grimes: A new song by the Canadian artist was co-written by Dunham's boyfriend Jack Antonoff, of Fun and Bleachers fame. Says Raval: "Jack is our secret weapon on the show. With him, we have access to so much: he's an amazing songwriter and producer, he has relationships… A lot of times, we'll just ask, 'What are you working on now? Taylor Swift?' I have no problem tapping into that connection." And did he ever. Encouraged by Raval and others to collaborate, Antonoff and Grimes came up with "Entropy," a rough mix of which Dunham played for Raval from her phone. "We instantly said, 'That's ours, don't give it to anyone,'" Raval recalls. "It ends one of my favorite episodes ever -- a big party event leads us on a very melancholy note but there's something so awesomely fun and energetic about this track that really plays against the moment."

This story first appeared in the Jan. 24 issue of Billboard.