Spontaneous is a 2020 American coming-of-age romantic black comedy horror film, written, produced and directed by Brian Duffield, in his directorial debut. It stars Katherine Langford, Charlie Plummer, Hayley Law, Piper Perabo, Rob Huebel and Yvonne Orji and is based on the 2016 novel of the same name by Aaron Starmer.

Plot

During a senior calculus class at Covington High, senior student Katelyn Ogden inexplicably explodes, spraying the surrounding students and classroom with blood. The police take the class into custody during an investigation, but aside from ruling out an attack, are unable to determine the cause of the explosion.