Saoirse Ronan is brilliant in 'The Outrun,' a film by Nora Fingscheidt about a woman battling alcoholism. It's based on a memoir by Amy Liptrot.

Saoirse Ronan appears in virtually every frame of “The Outrun,” and it's hard to imagine this poignant but brutal portrayal of an addiction and recovery journey without her.

Blind drunk at closing time, Rona — a bright, late-20s graduate student majoring in biology — has again pushed her luck and, literally kicking and screaming, provoked the bartender into tossing her out of a London pub onto the sidewalk.

“Outrun” rates as a personal triumph for Ronan, 30, who carries the film and is in every scene. It was Ronan’s husband, the “Slow Horses” star Jack Lowden, 34, who discovered the source material: Amy Liptrot’s bestselling memoir which Liptrot adapted for the screen.

Then there’s the ways addiction bifurcates her life. Rona is deeply passionate about ecological preservation. There’s nothing more she loves than the natural world and protecting it. Simultaneously, she grapples with a disease compelling her to destroy her body.