THERE ARE TWO formulas when it comes to rock and roll documentaries. The first is the sweeping exposé of a world-famous band or musician—you can expect some unreleased concert footage, some exclusive interviews, some new, shocking insight. The second template is the heartwarming and/or heart-wrenching story of an underdog who just won't quit—despite ghastly drug addictions, tragic deaths, or lack of chart-topping hits—where said subject presses on, never turning their back on their passion and livelihood.

You'd best believe a documentary about Jon Mikl Thor—the Canadian body builder turned heavy-metal frontman—will fall squarely into the latter formula.

I Am Thor traces the career of Thor, starting with his childhood superhero fantasies and his days as a Vegas showman who bent steel bars and blew up hot water bottles, before following through with his brush with stardom in the late '70s and early '80s with his band Thor; then wraps up with his comeback in the late '90s and a short European festival tour in the late '00s. The old footage and photos of Thor are fantastic, and his love for what he does stands out, particularly in the second half of the film.

But while I Am Thor's heart is in the right place, it's crippled by bias: Many of the details about record company snafus and "mismanagement" are glazed over, or brushed off with the "it just didn't work out" treatment. Meanwhile, most of the talking heads are friends, family, or fanboys; all of them speak of nothing but Thor's glory.

By the time it's all over, I Am Thor leaves you wondering if you're getting both sides of the story. Was Jon Mikl Thor really left at the curb, or was he the reason for his lack of fame and fortune? Is this an inspirational story, or are we watching the life of a delusional man? Thor's fans already know the answer to these queries—but for those new to the Thor legacy, I Am Thor ignores the answers to those important questions.