December, 1148; 543 AH: a small band of illustrious travellers gather on Marettimo, a fortress island off the coast of Norman Sicily, destination Brycgstow, England. Among them is geographer and luminary of Roger II’s court, Muhammad al-Idrisi, travelling in pursuit of his grand treatise, Nuzhatul Mushtaq. Finding safe passage on Captain Hajji's futuristic vessel, al-Jaariya, Idrisi shares conversation and adventures with an extraordinary array of characters, some human, on a tumultuous voyage where the darkest encounters are not with sea monsters or storms, but with the desires and contradictions burning at the very heart of their expedition.