SEATTLE — Between January and March of 2013, the Fleet Foxes frontman, Robin Pecknold, lived alone in a small house in Port Townsend, Wash., a wind-swept town on the northeast tip of the Olympic Peninsula — a two-hour ride from Seattle by car and ferry — that empties during the dark, chilly winters. He spent his days taking a 12-week woodworking course that emphasized labor-intensive traditional craftsmanship using hand tools. Most nights, he went for long runs through the town’s hills, streets and marinas.

It was a curious place to find the lead singer and sole songwriter of one of the most successful indie-rock bands of the past decade. Fleet Foxes’ first two albums of meticulous, expansive folk-rock have sold more than two million copies worldwide. But Mr. Pecknold’s life ran aground during the making of the Grammy-nominated 2011 album “Helplessness Blues.” His single-minded focus on the project and his constant interrogation of his own motivations and self-worth made for compelling music but toxic living.

On the album’s epic, introspective title track, he sings that he would “rather be a functioning cog in some great machinery serving something beyond me” and admits, “I don’t know what that will be/I’ll get back to you someday soon,” with an answer.

“Soon,” it turned out, was relative. When Fleet Foxes’ new album, “Crack-Up,” is released on Friday, June 16, it will be more than six years since “Helplessness Blues.” But the band is returning with a weighty, ambitious album of shape-shifting songs that builds on the exacting finger-plucked guitar melodies and cooing multipart harmonies central to its earlier music. At a time when indie-rock seems be growing more culturally marginal by the day, “Crack-Up” is a defiant artistic statement, an album that dares to feel important. It leaked more than a month before its scheduled release date, a frustrating turn of events but one the band ultimately found encouraging.