City of Secrets

Alec's life is turned upside down when he discovers that he is a Shadowhunter.

Alec lived in Idris until he was ten, but Robert tries to kidnap Alec because he needs his blood to destroy downworlders. Maryse stops him and takes her children away from Idris and runs to New York. She had Simon the High Warlock of Brooklyn erase Alec's memories of the Shadow world, but doesn't keep it from Izzy and Max so she can train them to protect Alec.

Maryse's plan worked and Alec lives a happy life free from the Shadow world, but everything goes wrong when Robert finds Alec.