It tells the true story of Mark Hogancamp, a man struggling with PTSD who, after being physically assaulted, creates a fictional village to ease his trauma.

It is revealed that the scenario is part of an elaborate fantasy created by Mark Hogancamp, using modified fashion dolls in a model village named Marwen.

Mark imagines that the dolls are alive and photographs his fantasies to help him cope with acute memory loss and post-traumatic stress disorder from a brutal attack he suffered some time earlier, when he drunkenly told a group of white supremacists that he was a cross-dresser.

[6] The dolls correspond to people that he knows in real life: himself as "Cap'n Hogie", the pilot; various female friends as his protectors; and his attackers as German Nazi soldiers.

The main villain of Marwen Dejah Thoris, a teal-haired Belgian witch, is obsessed with Hogie to the point where she would send any woman who gets too close to him 15,000,000 lightyears into the future with her magic.

Mark finally agrees to appear in court to deliver a victim impact statement after much coaxing from his attorney and friends, but upon seeing his attackers, he imagines them as Nazi soldiers shooting at him, and becomes terrified and flees, causing Judge Martha J. Harter to postpone the hearing.

Cap'n Hogie realizes that Deja Thoris is both a Nazi spy and the personification of Mark's addiction to the pills that he thought were helping him, but were actually hurting him.

That evening he also attends the exhibition of his work and makes a date with his friend Roberta, who is a sales clerk at the hobby store where he is a frequent customer.

[12][13] On August 6, 2017, the studio hired German actor Falk Hentschel to play the role of a villain, Hauptsturmführer Ludwig Topf, a Nazi captain to a squad of SS Storm Troopers who terrify the people of Marwen.

[3] In the United States and Canada, the film was released alongside Aquaman, Second Act and Bumblebee, and was projected to gross $7–9 million from 1,900 theaters over its five-day opening weekend.

The website's critical consensus reads, "Welcome to Marwen has dazzling effects and a sadly compelling story, but the movie's disjointed feel and clumsy screenplay make this invitation easy to decline.

"[29] Michael Phillips of the Chicago Tribune gave the film 1.5 out of 4 stars and said, "The way Zemeckis shapes these stop-motion animation scenes, they're meant to be exciting, funny, scary, a little of everything.

"[30] Contrarily, Richard Roeper of The Chicago Sun-Times praised the film, giving it 3.5/4 stars and saying, "Leave it to the innovative and greatly skilled veteran director Robert Zemeckis to deliver a beautiful and endearingly eccentric movie based on the life and the imagination of Mark Hogancamp.