In a small town in Massachusetts, four high school girls perform a ritual in an attempt to debunk the lore of Slender Man. When one of the girls goes mysteriously missing, they begin to suspect that she is, in fact, his latest victim.
Smooth advertising executive David is in a relationship with yoga teacher Juliette. Then his eye is caught by Sophie, the girlfriend of his best friend Wim, a fashion photographer. Things get completely out of hand during a campaign for augmented reality-glasses, for which David designs an avatar of the coveted Sophie.