Hollywood » Much as "24" has its roots in 9/11, 7/7 -- the day in 2005 that Islamic extremist suicide bombers hit the London transit system -- provides the deep background to "Britz," a two-part film by Peter Kosminsky ("White Oleander") about identity, prejudice and anti-terrorism in the land of the Magna Carta.

Airing Sunday and Monday on BBC America, it is more thoughtful than your usual American terrorism thriller, although the thinking is not always easy to follow.

The tale is told in two interlocking episodes, following the mostly separate paths of two British-born siblings of Pakistani heritage. Sohail (Riz Ahmed), whose story airs Sunday, is studying for the bar. His friends are mostly white, he's uninterested in religion and he identifies himself first and foremost as British and goes to work in London for MI5, the British intelligence agency.

Monday follows his younger sister, Nasima (Manjinder Virk), still living at home in Bradford (near Leeds, where the bombs used in the 7/7 attacks were manufactured). She's a medical student and leafleting activist protesting the new British police state, its abuses of power at home and its participation in the Iraq war; her boyfriend, whom she hides from her family, is black and not a Muslim. She's modern in all respects. Then the suicide of a friend sets her off on a more radical (although not, notably, Islamist) path. Brother and sister each lose a part of themselves, become dulled to the consequences of their actions. And both their paths lead to a park at Canary Wharf.

To say even a little about what happens would perhaps be to say too much, but generally speaking, Kosminsky is better here with moments than with motivations and better at creating scenes than at building them into a story. The whole is something less than the sum of its parts. But the parts are pretty good -- from minute to minute, as an experience of people and place, the film has much to offer.