Martha "Dumptruck" Dunnstock, portrayed by Carrie Lynn Certa, is a minor character of the cult classic film Heathers, and a secondary character in the musical. Martha is relentlessly teased throughout the film.
The first time Martha is shown, Heather Chandler forces Veronica Sawyer to forge a love note under Kurt's name. When Martha brings the note to Kurt, he laughs in her face and she storms out of the cafeteria. Veronica did not laugh, though, and she went over to the stand looking fed up, probably realizing that The Heathers were just toxically influencing her. Heather Chandler grabs her. “You wanted to be a member of the most powerful clique in school.” She said.
Not much is said about Martha's early life other than being shown that she was childhood friends with Heather Duke.
Martha is very overweight, has her brown hair cut short and dresses unfashionably. Living in a shallow society, the poor girl goes through hell for not fitting the mold of thinness. The Heathers do not respect her for her overweight self, and Veronica, becoming a Heather, also says Martha is fat. She could’ve been becoming a Heather because Heather Chandler And Veronica Sawyer’s poses were exactly the same. After they keep bullying her she runs out of the stage, crying. Veronica keeps on telling Martha that she is sorry but Martha keeps crying saying that she’s “lying about being sorry”.
Quiet, afraid, shy and emotionally bruised. Martha is one of the most tragic characters, and definetely the one who has it worse. She is a sensitive girl who dreams of loving and being loved, but for being overweight she is shunned and mistreated by others, and too afraid to stand up for herself.
When she can't take it anymore, she attempts suicide, but luckily survives.
In the ending of the movie when Veronica befriends her, we finally hear her voice and get a good glimpse of the sweet, sensible young woman who still keeps hoping for the best, despite everything she went through.
Martha is seen sitting in the gym after the murders of Heather Chandler, Kurt, and Ram. At first, it appears she is attending a sporting event but is really alone.
She spills a drink on herself and then the scene flashes to Martha walking into traffic with a suicide note pinned to the front of her shirt.
Luckily, she survives but is badly injured and ends up being wheelchair bound. Heather Duke continues to mock her for trying to "act popular" by committing suicide like Heather, Kurt, and Ram did, for which Veronica slaps Heather.
Martha Dunnstock and Heather Duke were close friends during their childhood. It isn't explained why the friendship ceased, but it is made clear that Heather Duke does not want anyone at Westerburg High to know about their past friendship.
At the end of the film, free at last of the Heathers' toxic influence, Veronica Sawyer invites Martha Dunnstock to hang out on prom night and watch movies with her. This is the start of their friendship.