Imam Mandi will rise in the last days of the world to fill the earth with justice. According to Sh'i beliefs, the twelfth Imam is Muhammad ibn Hasan Askarī. He went into minor occultation in his prime of life when his four deputies served as intermediaries between him and his followers. After sixty-nine years, he went into the major occultation and he will rise upon Divine Command. This book is a collection of thematically arranged hadiths based on major classical Shi'i hadīth sources, such as Bihār al-Anwār and Kamāl al-Dīn. The hadīths which have been collected relate to Imam Mahdī's birth; prime of life; minor and major occultations; deputies; signs and causes of his rising; and the fruits of his rising in the last days of the world.