Hans Thomas, the 12-year-old narrator, and his alcoholic father, another joker, are more satisfying characters than the purely functional Sophie and Alberto. Father and son embark on a journey from Norway to Greece to track down Hans Thomas's runaway mother. On the way they visit Legoland, where Dad exclaims: "Just imagine if all this suddenly came alive, Hans Thomas ... basically we ourselves are such live Lego figures." Alberto also used Lego to explain Democritus's theory of atoms, you may remember, but here the story-within-a-story, about the problematic relationship between creator and created, uses a different game as its paradigm.
Hans Thomas whiles away Dad's morning hangovers with lonely games of solitaire, which makes him all the more receptive to the tiny story-book he finds, about a man on a desert island whose only companions are a pack of playing cards. Before long the vividly imagined card-characters escape from their creator's brain and take on objective existence. They live in harmony with the shipwrecked sailor until the appearance of the mischievous joker prods them into self-consciousness (rather in the way that Sophie and Alberto become aware of their own fictional status), with disastrous results.
As Hans Thomas reads his book with the help of a magnifying-glass given to him by a mysterious dwarf, Dad roams around philosophising ("If our brain was simple enough for us to understand it, we would be so stupid we wouldn't be able to understand it after all"), and "bumming" jokers from any card-players he encounters. In Greece, Dad lectures his son on philosophy, myths and the Oracle, but the device of the journey makes these spurts of didacticism seem less contrived, and Hans Thomas, half awed, half humorously indulgent towards his baffling father, is a much more satisfactory focus for the reader than the shadowy Sophie.
Like Gaarder's debut, The Solitaire Mystery owes a debt to Lewis Carroll: the riddling, self-important playing-cards are straight out of Wonderland. Carroll, of course, was an Oxford don who poked fun at current philosophical theories in his stories. Since The Solitaire Mystery is not a straightforward trot through the centuries like Sophie's World, what, to use a term from that book, is its "philosophical project"? Simply to remind readers to cherish a sense of wonder at the world's haunting strangeness. The child mature enough to understand this will already have had some of that sense of wonder rubbed off; but as a sparkling injunction to be forever humorous, optimistic and above all curious, this is a book of marvels.