As pop star Celeste, Natalie Portman pushes herself to outsize, Lady Gaga-like levels. It’s an inspired transformation, but not profound enough to redeem a pretentious blockbuster imposter. The film opens with a 1999-set prologue, in which teen Celeste is nearly killed in a high school massacre. She composes an inspirational ballad in the aftermath, which turns into a hit. Subsequent international tragedies correspond with Celeste’s rising career. We’re either supposed to feel sorry for her or we’re being mocked for our celebrity-culture adulation. So A Star Is Born this is not.