Baudolino, son of a Ligurian peasant, adopted son of the Emperor Frederic Barbarossa, rescues Niketas, a Byzantine court official, during the Fourth Crusade's sack of Constantinople in 1204 and during the succeeding days tells him his life story. It is a story, a game even, of two halves, for Baudolino is nothing if not ludic: ironic, parodic, fantastic, funny, tragic, occasionally tiresome, self-indulgent and above all playful. The first half recounts how Baudolino goes to school in Paris where he meets the friends who will accompany him on most of his adventures. The most notable of these is The Poet, identified with the historical Arch Poet. After Paris Baudolino drifts between Frederick's perambulating court as the emperor seeks to bind the reluctant cities of north Italy to the empire, and the people he grew up amongst, including his real father. A wooden cup belonging to his real father is taken to be the Grasal or Holy Grail and acts as the link to the second half. So far the story has inhabited a recreation of the period based on real events, with historical characters. But by now we have reached 1189, the Third Crusade. As they pass through Constantinople Baudolino and his friends, employed as Barbarossa's closest minders, pick up Zosimos, a villain. Barbarossa dies mysteriously in a locked room, Baudolino and his friends fake his historical drowning and set off on a quest to find the kingdom of Prester John, a quest which is also a pursuit of Zosimos, the presumed assassin. At this point we leave the real world of the chronicles and enter that of Mandeville's Travels. Clearly Eco has mined Mandeville and the sources behind Mandeville - we meet the sciapodes, the anthropophagi, and even men whose heads grow beneath their shoulders, weird forests, rivers of stones and so on, all re-created here with often nightmareish vigour. Having survived all sorts of horrors Baudolino meets a Lady and her unicorn. She is an avatar of Hypatia, the neo-platonist murdered by Christian monks in 415, who reveals to him a neo-platonic vision of the Unique which chimes with much modern thinking about the nature of the creative impulse we used to call god. In short we are back with Eco's main concerns as a philosopher and even mystic, which informed, in a more discreet way, The Name of the Rose. Baudolino plays with philosophy, physics and metaphysics, geology, minerology, theology, just about every -ology you can think of. It is outrageously inventive, outrageously derivative. Yet the characters of Baudolino, The Poet, Barbarossa, Zosimos, the sciapode Gavagai and finally Hypatia herself are deeply realized and give the whole rambling mass a unity and human interest which make it Eco's most approachable book since The Name of the Rose. Force-fed as we are by anglophone realism (pace Pullman et al.), it reminds us how boundless the possibilities of extended fiction are. Finally,William Weaver's translation allows us to forget it is a translation, and one can't say better than that. Julian Rathbone's latest novel is A Very English Agent. (Kirkus UK)