A young woman who is a successful model, and is also engaged to be married, and who has twice attempted suicide in the past, is chosen by a secretive and distant association of Catholic priests to be the next "sentinel" to the gateway to Hell, which apparently goes through a creepy old, but well maintained Brooklyn apartment building. Its tenants take the stairway up and can reincarnate themselves, but apparently can't escape as long as a sentinel is there to block the way. The previous one(John Carradine) is about dead, so she, by fate or whatever, becomes the next one, and the doomed must get her to kill herself in order for them to be free. Lots of interesting details lie under the surface, her relationship with her father, the stories of the doomed, her fiancé, so one can pass this off as cheap exploitation horror, but given the sets, the great cast, and overall level of bizarreness, this is definitely worth seeing.