Four patients, considered criminally insane, Dave, Loner, Eric and Geoff, escape from the institution. Hunted down and surrounded by the police, the escapees decide to take the occupants of a house hostage until the situation calms. The house they enter is named Oniria and it is where Vivianne Levant, Dave’s psychiatrist, resides. Impossible to discern from the exterior, Oniria is structured upon a deep labyrinth-like basement where Vivianne conducts experiments on criminals...

While searching for Vivianne, strange characters - the embodiments of Vivianne’s patients’ dreams - appear to come alive and confront the escapees. Dave, Loner, Eric and Geoff are forced to confront each other and their greatest fears.

As the night wanes and slowly turns to morn, the men fall into one hauntingly inexplicable event after another. Vivianne tries to explain the dreams and images, but the men cannot understand. While the situation degenerates into chaos, one begs to ask:

Exactly who is holding whom hostage?