Time travel is every person's fantasy at one point or another... but in "A Tale of Time City," it really isn't nearly as fun as you would expect. Diana Wynne-Jones spins up an elaborate, wryly humorous scifi/fantasy where it turns out that time travel is a bit more complex than anyone expected, with plenty of memorable characters and weird time periods. 
 It's London, 1939, and the Blitz is looming over London. Vivian Smith is leaving to stay in the country with a cousin, only to be dragged into another world by a strange boy. His name is Jonathan Lee and his younger cousin Sam is helping him. They think that she is the extremely important Time Lady, who is the only one who can wake Time City's founder, Faber John. 
 Time City, where Jonathan and Sam live, is a futuristic civilization existing outside of time, and observing it closely. And grabbing a person from an unstable era such as "Twenty Century" is a serious offense -- both for them and for Vivian. 
 The boys hastily disguise her as their cousin Vivian. Jonathan's family welcomes Vivian with open arms, but she still has to get used to a strange world filled with invisible furniture, androids -- and a future timeline for Earth that boggles the mind. But Time City itself is in danger. The timekeeping "polarities" are being stolen, and Faber John's stone is cracking and crumbling. The only ones who can save the City are the three children. 
 "A Tale of Time City" is a complex story -- sometimes too much, since all the time-hopping, weird eras and secondary characters get rather confusing for the reader. However, it's the GOOD kind of "complex," with constant twists and mysteries interwoven into a simple sci-fantasy story, set in a futuristic city that is anchored OUTSIDE time itself. 
 Jones sculpts a plausible timekeeping civilization, with all sorts of weird details that Vivian has to accustom herself to (strange foods, robots, clothing, customs). She unfolds the plot gradually like a scroll, revealing surprises embedded in the surface as it rolls out, but with plenty of kooky humor and wry dialogue (the "hunt the slipper!" scene). 
 Vivian is a likable protagonist in the classic British kids' lit mold -- a plucky preteen with plenty of guts and an iron spine, sort of like a modernized version of a C.S. Lewis heroine (and one suspects that the opening scenes were a homage to Lewis). Jonathan is a likable if sometimes bumbling kid with an earnest desire to help Time City, and Elio is a pleasant "good android" sidekick for them. Sam's obsession with pies gets a bit annoying, though. 
 Out of Diana Wynne-Jones' colorful bibliography, "A Tale of Time City" is one of her most underrated stories -- a clever, witty sci-fantasy with plenty of twists.