Of all the movies I've seen depicting The Troubles in Northern Ireland -- and there have been some powerful films on the subject -- "Titanic Town" is the first one that really drove home to this outsider what it must have been like to live in a neighborhood where sniper fire is an everyday occurrence, where the hulks of bombed-out cars sit in the town square and where a quiet residential street can be invaded at any moment by columns of soldiers, armed to the teeth and coming to drag away one or more of your neighbors.

The most visceral moment in this tense but hopeful film, about an Irish Catholic mother of four who takes it upon herself to stop the undeclared war, comes in the middle of the night when the teenage daughter of this housewife-activist wakes up to the sight of paramilitary guerillas taking up attack positions in her front yard. The scene gave me chills, plain and simple.

Our passport into this perilous world is Bernie McPhelimy, a real-life woman of dogged determination who in the 1970s jumped headlong into the quagmire that was (and still is) the bitter, violent, terrorizing clash between Catholic Irish Republicans and Protestant, Britain-backed Unionists.

Played by the outstanding Julie Walters ("Educating Rita") as a fretful nagging nelly who has her heart in the right place but fusses embarrassingly over her children and badgers her haggard husband (Ciaran Hinds), Bernie is at once endearing and annoying. These character traits come in handy when, after seeing an innocent friend gunned down in the street, she publicly condemns the IRA for their terrorist tactics, instantly turning her family into outcast and virtual prisoners in their own home.

Bernie has plenty of ire for the British as well, and her unassuming but incensed rhetoric soon garners her national attention. Being far too trusting and not at all media-savvy, she finds herself in way over her head -- often misunderstood, vilified by her own people and patted on the head by a manipulative British government when she dons her Sunday best to present stodgy officials with a list of demands as they patronize her with chatty promises and a cup of tea.

The film also follows Bernie's mortified 16-year-old daughter Annie (Nuala O'Neill, making an indelible impression in her first acting role), who becomes an object of scorn at school and finds solace in the arms of a young medical student (Ciaran McMenamin), who is more than he appears to be.

Director Roger Michell ("Notting Hill") maintains an incredibly limber balance between humor and melancholy in "Titanic Town." During a military seizure early in the film, Bernie sends her kids upstairs to make their beds so she won't be embarrassed if the soldiers search their house. Such light comedic touches seem perfectly natural coming from Walters, who gives a flawless performance as a conservative middle-aged woman who tires of being flustered and merely rattling her handbag, and becomes a obstinate force for peace.

But while the film is in some ways light-hearted, Michell never lets you forget the chaotic state in which the McPhelimys live. The children walk to school past burned-out buildings, army checkpoints and soldiers with rifles at the ready. On a date Annie and her beau barely escape from a bus when it's attacked and burned by a mob of angry Catholic teenagers. And it's not unusual for the army to sweep down their street for a round of seemingly random arrests.

"Titanic Town" makes such moments all the more striking by presenting them almost parenthetically. It's abundantly clear that such things have become a way of life for the people on the McPhelimy's street, and in fact in their whole country.