Even now, knowing all that we do about his deception, Lance Armstrong can be remarkably convincing. As he denies doping allegations in the documentary The Armstrong Lie, you're still halfway inclined to believe him. His conviction is just that persuasive and, consequently, so unnerving. Astute documentarian Alex Gibney (Taxi to the Dark Side) was apparently hoodwinked as well, and he took a rare foray into inspirational storytelling to chronicle the cyclist and cancer survivor's 2009 comeback. But when Armstrong's failed bid for an eighth Tour de France title resulted in him being outed as a cheat, Gibney was forced back to the drawing board. Alas, the finished film often feels like anything but: It's a first draft instead of a treatise. Musings on the "moral relativism" of competition, previously reported details about the complexity of Armstrong's cover-up (including some audacious blood transfusions) and a glut of 2009 Tour footage join Gibney's earnest voice-over, which relates his desire for a reasonable explanation from Armstrong about his deceitfulness. Problem is, Gibney never manages to equal his subject's conviction. Faced with an opponent desperately clinging to the last vestiges of his reputation, Gibney uncharacteristically fails to fully pull back the curtain.

Critic's Grade: C

SEE IT: The Armstrong Lie is rated R. It opens Friday at Cinema 21.