Harriet Tubman was an inspiration. After escaping slavery in Maryland by walking 100 perilous miles to Philadelphia, she went back for her family. Then she went back again. And again. In addition to personally guiding over 70 slaves to freedom, she became an icon of emancipation, a model of courage and encouragement. Someday someone will make a movie worthy of this freedom fighter’s heroism. This isn’t it.

Biopics about noble and inspiring subjects are not immune from filmmaking criticisms.

This one is prosaic, perfunctory and preachy, frequently undercutting Tubman’s multi-faceted, complex personality by portraying her as a vessel for God. Clumsy action-movie sequences and a bunch of made-up filler fail to dispel its made-for-TV, history-class vibe, and the swelling score is obvious.

Fortunately, a committed, Oscar-nominated performance in the title role by Britain’s Cynthia Erivo elevates all this to a watchable level, but otherwise the script is risk-free and the acting so-so (comically so with Joe Alwyn as her mustache-twirling former owner).

Finally, the film makes the mistake of thinking it’s enough to tell us of Tubman’s greatness when it should have been showing us.

(125 min)