The Báb: The Herald of the Day of Days by H. M. Balyuzi narrates the transformative journey of Mullá Ḥusayn, the first believer in the Báb, the Herald of a new Revelation. From the awe-inspiring encounter with the Promised One to the spread of the Bábí Faith and the persecution faced by its followers, the book delves into the spiritual revolution ignited by the Báb's message of unity, justice, and love. It explores the Báb's teachings, interactions, and martyrdom, shedding light on the profound impact of his mission on humanity.