In 1258 Wazir Marzban saves the House of Wisdom, the great library created in the round city of Baghdad, from destruction by the Mongol army. In 2018 Professor Hakim Azzi seeks out Amanishakete and Sabine in London to help rescue the entire library that history had wrongly recorded was totally destroyed by the Mongol Horde.
But Azzi has already sold two documents from the House of Wisdom on the open market, starting a race between Wolfram von Sternberg a German Count and his son Paul, Edward Maltravers a less than honest dealer in antiquities and Amanishakete and Sabine, to find the House of Wisdom.
When the dimensional veil, created by Marzban to protect the House of Wisdom, goes wrong they all find themselves confronted by the Mongols in the year 1258.