Jainism does not have a single “one book.” The Jain scriptures are a collection of texts that differ a bit between the two main traditions (Śvētāmbara and Digambara).

• Universal concise text: Tattvartha Sutra by Umāsvāti. This is widely respected by both Śvētāmbara and Digambara as a complete summary of Jain doctrine, ethics, and practice.
• Śvētāmbara canon (Agamas and related texts): the Agama literature in Prakrit, including other well-known sutras like Aṅga, Upāṅga, and later dissections such as SutrakRtaṅga, Ācāranga Sūtra, and Uttarādhyāna Sūtra.
• Digambara canon: often emphasizes different collections and emphasis, with texts like the Kalpa Sūtra (birth stories of the Tirthankaras) being particularly central in their traditional compilations.
• Other important Jain works across both traditions include commentaries, devotional stotras, and philosophical treatises, but the above are the core reference points.

If you’d like, I can narrow it down to a specific tradition (Śvētāmbara or Digambara) and suggest the exact texts and their key topics.