Director Jim Sheridan (who made the memorable “My Left Foot” with Day-Lewis) tells his gripping tale with a fury that stokes up an audience the way early Costa Gavras movies (“Z”) used to do. But there’s more to his story (co-written by Sheridan and Terry George) than good, scruffy Irish victims and rabidly bad English heavies–though there’s plenty of that. It’s also the story of Gerry Conlon’s relationship with his father (Pete Postlethwaite), a man he despises until, by cruel fate, they become cell-mates in prison and are forced to hammer out a radical change of heart.

Day-Lewis’s Gerry is a rich creation. A hotheaded flake and petty criminal more interested in getting loaded than in politics, he flees to London after falling into trouble with both the Brits and the IRA in Belfast, spends time in a hippie squat (the “free love” era is swiftly, hilariously evoked) and on the night of the bombing makes a big score robbing a prostitute’s apartment. One can understand why his father has contempt for him, and why he can’t tolerate his sickly, oppressively upright dad. in jail he’s politicized by the IRA terrorist Joe McAndrew (Don Baker), a kind of surrogate Bad Father he must reject before he can make his peace with his real father. Day-Lewis takes us through Gerry’s turbulent conversions with fierce, unsentimental conviction. Emma Thompson plays Gareth Peirce, the lawyer who, five years into the Conlons’ incarceration, takes up the case and slowly wins Gerry’s trust. It’s not a big role, but like everything involved in this fleet, impassioned movie, it’s lit with fervor.