In Assassin's Creed Mirage, Basim Ibn Ishaq is a thief in ninth-century Baghdad before becoming an Assassin.
Basim begins the game as a street thief living in Anbar, a settlement near Baghdad. He works with his friend Nehal and dreams of joining the Hidden Ones. After a major theft brings him into conflict with powerful enemies, Basim escapes to the Hidden Ones' bureau and starts formal training under Roshan.
Mirage is set during the Islamic Golden Age, primarily in Abbasid Baghdad. The city is divided into districts with different social and political identities, and Basim's missions emphasize investigation, stealth, pickpocketing, and carefully planned assassinations. The game presents an earlier stage of the organization that later becomes known as the Assassin Brotherhood.
Basim should not be confused with Bayek, who is a Medjay in Origins, or with Altaïr, who is already an Assassin at the beginning of the first game. Mirage focuses on Basim's transformation from thief to Hidden One.