After receiving mysterious letters Ash and Pikachu set out to find the meaning behind them, on their small journey through Kanto they met up with two old friends Brock and Misty who have decided to travel with Ash to find the meaning of the letters, he also regained his old Pokemon Pidgeot, Butterfree, Primeape and a new capture of an old friend Haunter. After finding out Bill is Gary's dad and Prof Oak's son they received a letter addressed to Ash from him.

Ash and Pikachu are back in Kanto helping Prof Oak. at his Pokemon lab but when a mysterious old man storms into the lab and hands Ash a weird letter everything changes, as the letters seem to bring Ash and Pikachu back through their journeys and further and further away from home as they follow and try and figure out what these letters mean.