Anna Margaret Hollyman, left, and Andrea Suárez Paz in Sister Aimee (Carlos Valdes-Lora/Asleep in the Sea)

If Sister Aimee were an animal, would it be a shaggy dog or a lark? The whimsical road movie about a runaway evangelist possesses elements of both. Viewers will detect elements of Madeleine Olnek’s recent Wild Nights with Emily, a remixed/drunk history version of the life of Emily Dickinson, or a loopier version of the Coen Brothers’ picaresque O Brother, Where Art Thou?

Writers and co-directors Samantha Buck and Marie Schlingmann reconstruct a mysterious interlude in the life of Aimee Semple McPherson, the 1920s real-life holy roller who packed churches with exuberant hoedowns of healing, song, and dance. One day in 1926, the saintly Aimee “evaporated,” in the teary words of her assistant, supposedly drowning in the ocean. But suspicions grew around the sudden disappearance, with rumors spreading that McPherson had gone on a bender to Mexico in the company of a married man.

Sister Aimee takes many imaginative leaps in imaging the extended lost weekend. The adventure starts fast when Aimee friskily beds and then takes up with an earnest, aging boy/author (Michael Mosley) bent on taking a heroic Mexican expedition. The two hire a tight-lipped female guide (Andrea Suárez Paz, whose granite charisma overshadows everyone else) to help them navigate around hot spots. The trio is soon off to tangle with Mexican revolutionaries, smuggle a cache of hot machine guns, and pursue shenanigans.

As a backdrop to the action, the script tries to serve up some intel on its complicated anti-heroine, but comes up light. Flashbacks to disgruntled detectives interrogating Aimee’s relatives, rivals, and exes attempt to paint a character study of the mysterious preacher, with more folksy atmosphere gleaned than insight. Budget constraints don’t allow scenes of McPherson famously whipping up the crowds, although we do get a taste of her charisma later on.

Newspaper headlines alert the trio that parishioners and authorities are on to the fugitives’ ruse, but they don’t seem to spark much urgency in the peregrinations around the desert. McPherson’s flight and rather listless romance play out in a very of-the-moment mix of deadpan quirk and off-the-wall antics.

Results are uneven but charming, helped by cinematographer Carlos Valdes-Lora’s doing everything he can with a vintage car moving through baleful Southwestern landscapes. Although lead actress Anna Margaret Hollyman does not have a deep characterization to explore, her deft performance keeps us off-balance, intrigued, and not necessarily sure who we are watching. In all, a light diversion with the pleasures that come when a modern wink accents an old-time yarn.