Exclusive song premiere: Imaginary Future's "Forever On Your Side"

For Imaginary Future's upcoming album, singer Jesse Epstein tapped into what he knew best: his life.

Called "Sunlight," the new set is being described as a love letter to Epstein's wife, Kina Grannis. It features 11 songs -- one for each year of their relationship.

One of the tracks, called "Forever On Your Side," which makes its exclusive debut today on CBSNews.com, features vocals from Grannis.

"When I begin the songwriting process, I often start with an image in mind," Epstein told CBS News. "It helps me get to the emotional place I want to capture. 'Forever On Your Side' began with an image of me and my wife Kina, sitting on the edge of a boat in the South Pacific ocean. We're leaning off the side, in our scuba gear, about to head to the bottom of the ocean and swim with some sharks. It was an ideal place to start a song. 'Forever On Your Side' is about more than always being there for someone. It's about making a life together into an adventure and helping each other become better people every day."

Take a listen to the track here:

"Sunlight" arrives on March 24.