NEW YORK -- Mary J. Blige needed some therapy. We all do sometimes, right? But few of us travel more than 3,400 miles to get it. The Queen of Hip-Hop Soul had her reasons, though, and she details them with raw honesty in the documentary "The London Sessions," which had its Tribeca Film Festival premiere at the Beacon Theatre on Thursday night.

"I get a little nervous about telling everything now because I've told so much," Mary tells one of the songwriters working on what will become her 13th album, the deep-house-infleunced "London Sessions." Still, the soul icon from Yonkers' Schlobohm Houses goes on to reveal that being an R&B singer in the States -- albeit a record 30-times Grammy-nominated, multiplatinum one -- has left her feeling "stagnant" and "stuck."

With encouragement from super-producer Rodney "Darkchild" Jerkins and an invitation from a series of Brit hitmakers, including Sam Smith; the "20-year-olds from Surrey," Disclosure; Sam Romans; and Jimmy Napes, Blige puts in work over the course of 20 days. She's buoyed by the vibe in the U.K. -- even taking us to her favorite fish-and-chips spot -- where she says "artists have freedom to do what they love."

But as she opens up to Romans in a tear-filled writing session for the breathtaking ballad "Doubt," we see that Mary still has to put that negative "voice in [her] head" in a half-nelson from time to time. Blige's last full-length studio album, 2011's My Life II... The Journey Continues (Act 1), was generally well-recieved by critics but fans largely seemed to ignore it: of the four singles pushed to radio, only one saw any chart success. (In a floor-shaking live performance after the documentary screening, Blige alluded vaguely to personal trials in the four yours that followed the release of that album.)

All of that seems to drive the "Sessions" album. Mary sounds invigorated, her voice somehow even richer, but she also seems fortified by the love from these young artists. In one scene, Sam Smith, who was born the same year Blige dropped her hip-hop-soaked debut album, What's the 411? in 1992, gets emotional remembering the first time he heard the 44-year-old's cover of his smash "Stay With Me." But the "untouchable goddess," as Smith calls her, seems just as grateful to be in the 22-year-old's presence.

That dynamic was admittedly surprising to watch for this lifelong MJB devotee, and it's echoed again when Blige meets Mitch Winehouse for tea and confesses she wants to make an album Amy "would be proud of."

Blige goes to London in search of a new sound though, and she finds it. Recording for the first time with a live band, "The London Sessions" -- with songs like "Whole Damn Year," "Nobody But You" and "Pick Me Up" -- is a revelation that manages to fuse the singer's signature soul with the kind of gritty dance that no one would confuse with the four-on-the-floor trend that took root on our Billboard charts a few years ago.

You're "always gonna be relevant as long as you tell the truth," someone says near the end of the doc. If truth-telling is the metric for relevancy, then Mary should always be in vogue.