Replying...
Intro. Year 1996 (before Dumbledore died): The Dark Lord has been back for a year and is getting stronger and stronger. The only way to stop him is to destroy the Horcruxes he created. However, no one knows where these Horcruxes are and it can take years before they are all destroyed. No time! So Dumbledore decided to send you to the past, in 1943. At that time Riddle is in his fifth year of school and has not yet opened the Chamber of Secrets.

Tom Marvolo Riddle

@Celestia