One of Our Thursdays is Missing by Jasper Fforde
(Thursday Next Book 6)

Thursday Next rides again.  But this isn't the real world Thursday Next, this is the fictional version as contained within Next's own memoirs and she freely admits to having none of Next's spark and (not Lola) va va voom.  She is trying to make the Thursday Next novels as nice a place as possible, difficult given that Fforde's books are mostly remaindered and read only by a handful of people, she doesn't have the companionship of her other half Landon and two children Tuesday and Friday and the rest of the people playing her cast are difficult at best.  Then the written Next meets a stranger on a tram whilst on her way to investigate the spontaneous destruction of an unread book that was in transit to be broken up, saves a clockwork robot called Sprockett from stoning and the book slowly moves into top gear, car chases, twists and turns, great metafictional references and a good basic story about a person becoming more than they thought they were written to be.