Judi Dench and Steve Coogan in ‘Philomena.’ (Photo courtesy the Karpel Group)

With its winning combination of comedy, moral uplift and righteous indignation, and the surprisingly effective pairing of Dame Judi Dench and Steve Coogan, “Philomena” is an excellent addition to your holiday festivities.

The film is based on the true story of Philomena Lee (Dench), an unwed mother in Ireland who was forced to give her son up for adoption and to work in a convent laundry to atone for her sins and to reimburse the nuns for their obstetrical care. (The outrageous treatment of women like Philomena is explored in the award-winning 2002 documentary “The Magdalena Sisters.”)

With the help of former journalist and disgraced politician Martin Sixsmith (Coogan), she decides to track down her son. After being stonewalled by the nuns at the convent in Roscrea where Philomena was confined, the unlikely duo travel to Washington to follow up some promising leads.

Sixsmith discovers that Michael was adopted by wealthy American parents and ended up as a closeted advisor to President Ronald Reagan. Philomena is devastated to learn that her son died of AIDS, but the unlikely duo decide to track down Michael’s friends and family to find out more about the young man. Their road trip is both sad and funny, bringing together Philomena’s amusing observations of American life (she can’t wait to watch “Big Momma’s House” on the hotel TV) and the moving memories of Michael’s sister (who has been adopted from the same convent), female friend (and beard) and widower.

The screenplay by Coogan and Jeff Pope (based on Sixsmith’s memoir) deftly weaves together Philomena’s sexual indiscretion with her son’s repressive politics and closeted life, her unshaken faith in the Catholic Church against Sixsmith’s world-weary cynicism and atheism, and her belief in forgiveness versus the unyielding and unchanging judgments of the nuns. It leavens these serious themes with some delicious comic moments — Sixsmith’s interactions with his editor and former colleagues, Philomena’s delights at the perks of traveling on an expense account, and especially Philomena regaling the exasperated Sixsmith with the convoluted plot of one of her beloved romance novels.

But despite its many strengths, the screenplay does not fully manage to make the real-life story believable as a free-standing movie. For example, although we learn that Philomena has married and had children and moved to London, we never find out any details about her adult life. Likewise, we never learn in any detail about the scandal that has derailed Sixsmith’s high-flying career. These details could have amplified the powerful themes of redemption, betrayal and secrecy in powerful ways.

More seriously, though, the actions of the supporting characters are unmotivated. Michael’s widower, for example, goes to great lengths to avoid Martin and Philomena, but we never know why, and Michael himself remains a closeted but pleasant cipher.

Despite these flaws, the center of this thoroughly enjoyable movie is the stellar performance of Dame Judi Dench. She creates a richly multi-faceted character with great sensitivity and restraint. Her performance is ably echoed by the talented Sophie Kennedy Clark as the young Philomena in well-written flashback sequences. Both actresses bring to vivid life Philomena’s sensual delight in the fling that resulted in her pregnancy and the psychic and physical horrors of her cruel treatment by the avaricious nuns, as well the deep belief in the possibilities of human nature that brings about the powerful acts of forgiveness that cap the movie.

Dench is also well-supported by Coogan, who is best known for his comic turns in such movie as “Hamlet 2,” but shines in the more dramatic role of the disgraced politician Martin Sixsmith. As both writer and director, Coogan avoids the sentimental clichés that could have bogged the movie down and fully embraces the less savory aspects of Sixsmith’s character to make him a more effective foil to Philomena.

Both funny and inspirational, “Philomena” is satisfying holiday-season cinematic fare. It’s playing at Landmark E Street, Bethesda Row Cinemas and other area theaters.