Reverend Michael Hill (Edward Herrmann) and his two children arrive in a mid-sized California city as the new minister at North Avenue Presbyterian Church. The secretary/music director for the church, Anne (Susan Clark), is wary of the changes Hill intends to implement. Hill wants to get people involved, and asks the elderly Mrs. Rose Rafferty (Patsy Kelly) to handle the church's sinking fund.On his first Sunday, Hill learns from Mrs. Rafferty that her gambling husband Delaney (Douglas Fowley) bet all the sinking fund money on a horse race. Hill delivers a sermon less than 15 seconds long, then rapidly escorts Mrs. Rafferty out the church as astonished worshipers watch. She leads him to the bookie, hidden behind a dry-cleaning shop, and meets Harry the Hat (Alan Hale, Jr.), who recommends that Hill let the bet ride. Hill's horse loses and he is thrown out of the betting parlor. Hill summons the police, but the booking joint has been skillfully removed.That evening, Hill delivers a tirade against the organized crime in the city during a local television broadcast. He is chastised by his presbytery superiors for the tirade, and is urged to go out and build church membership in the area. His only success is with a rock band called Strawberry Shortcake, who he recruits to "jazz up" the music at church. As a result, Anne resigns as music director.A few days later, two treasury agents for the US government arrive: Marvin Fogleman (Michael Constantine) and Tom Voohries (Steve Franken). They want Hill to help them close down the town's gambling racket by recruiting some men from the church to place bets that the agents will watch. Hill cannot find any men to help, but hits upon the idea of using women. Hill calls together five women from the church whom include; Rose Rafferty; single mother Vicki Simms (Barbara Harris); man-hungry divorcee Claire Porter (Cloris Leachman); bride-to-be and career woman Jane Adams (Karen Valentine); and Cleo Jackson (Virgina Capers), who's husband owns a mechanic garage.Over the next day, the five women attempt to place bets in the company of the Treasury agents, but with disastrous clumsiness as their covers are blown due to their ineptness and bad luck.The team changes tactics to try to go after the "bank" that the gangsters use, tailing the mob's deliverymen through town while Hill coordinates using a map at the church office and keeping in touch by CB radio in the ladies cars. Delaney is forced to dress up as a woman to accompany his Rose since his wife does not drive. But after a few days of loosing the delivery car, two gangsters subsequently appear at the church during services and identify the women.Anne discovers the operation, even as Hill defends the Irregulars as keeping the gangsters off balance. After Hill refuses to back down from calling off the operation, Anne resigns from the secretary position. Later that night, the gangsters bomb the church.Hill is shocked at the gangsters' act, and seems ready to give in, but to his surprise, Anne wants to join the fight. They do so, and continue to hammer the gangsters' movements around town. Meanwhile, Hill receives word that the pulpit has been declared vacant and North Avenue will be discontinued as a church entity.Dr. Victor Fulton (Herb Voland), a representative from presbytery, arrives to discuss the closure with Hill. Anne picks up two more presbytery representatives at the airport whom are Dr. Rheems (Ruth Buzzi) and Rev. Samuels. But while driving them to the church, she recognizes one of the mob's deliverymen in a passing trailer and realizes she may be able to find the bank. She tracks the deliveryman to an isolated warehouse compound. Within minutes, all the Irregulars besiege the place as the gangsters attempt a frantic escape with their bank. A "demolition derby" ensues, the crooks are stopped, and the evidence is seized.The following Sunday, Hill's congregation gathers outside the gutted church while he delivers news of the indictments against the mob and of the closing of the church. However, Dr. Fulton steps in to proclaim that North Avenue has a new lease on lifeit will be rebuilt. The youthful band starts the music again as everyone rejoices.