Rough synopsis for "Time ghost"

Alana lives in a world filled with pain and despair, a world of the future so overpopulated that people are forced to live off rations and her people are the only hope. The “time ghosts” - people that can travel back in time and appear as the ghosts of the past. But with the “poltergeists” watching their every move will they save the world in time or is there more to this desolate world than meets the eye?