A solar storm destroys all electronic communications and the world returns to the steam age. The protagonist is one of the few postmen who can tame "carrier pigeons", but he delivers more than just letters - each letter comes with the sender's "memory fragments", allowing him to briefly experience the other person's past.
A blank letter without a signature, but in the fragment is a picture of his own murder in the future. In order to rewrite his destiny, the protagonist must travel through the radiation zone and deliver the letter to the "sender" within seven days, but all clues point to a perished city.
