The smart, solidly Masterpiece Theater-caliber Amazing Grace follows late 18th-/early 19th-century politician William Wilberforce’s (Welshman Ioan Gruffudd) nearly 20-year parliamentary campaign to end the British slave trade, finally scoring victory with the Slave Trade Act of 1807. Grace opens with an ill, laudanum-drinking, God-fearing Wilberforce weakened by constant parliamentary defeat and haunted by the atrocities of the slave trade of which he’s seen. And in textbook underdog fashion, director Michael Apted flashes back to dramatize how Wilberforce got there—primarily his lifelong friendship with eventual prime minister William Pitt (Benedict Cumberbatch) and how religion shaped Wilberforce’s thought—before settling in for Wilberforce’s final, uplifting victorious push. Credit Gruffudd for making the legend a man—this friend to animals, feeder of the poor, and crusader for social justice would seem too much an earthbound saint were not for the behavioral quirks, social awkwardness, and stiff goofiness that Gruffudd imbues into the performance. And he gets heaps of help from screenwriter Steven Knight’s (Dirty Pretty Things) witty, sharp script and a robust supporting cast that includes hatchet-faced Ciarán Hinds as a parliamentary foe, Rufus Sewell as a radical abolitionist, and the great Michael Gambon as a politically savvy elder statesman MP.