Dark Tales - Hidden Mystery

We have often heard or seen in the movies about people that talk with the dead. Also there are numerous stories about ghosts or zombies, about unfinished missions of the dead that has to be fulfilled in order to get peace and who knows what else but everything seems to be a speculation.

This is something really strange since we don't have any certain information about what happens with the souls after dead. Every religion and believing has its own explanation and everyone could believe in whatever he thinks is right but no one doesn't know how the things work for sure.