Title: A Tale of Time City
Author: Diana Wynne Jones
Publisher: Methuen & Company, Limited, 1987
A Tale of Time City is a stand-alone children's science fiction novel by Diana Wynne Jones. It was written during what I consider to be the peak of her career, a year after Howl's Moving Castle and a year before The Lives of Christopher Chant. AToTC is not in any way connected with either of these books or the resulting series, but it shares their quick-moving, child-centric sense of adventure. It is her only work that is straight-up science fiction -- and as you might expect, it deals with time travel.
The story starts with 12-year-old Vivian Smith, who is sent out to the country to live with her cousin during the bombing of London. She never makes to to her cousin's house, however, as a time traveler is waiting on the train platform to kidnap her and take her back to the distant future.
This would be unfortunate in any case, but it emerges that her kidnappers are not registered time travelers, but a couple of young boys who broke into the offices of the time patrol to illegally time-travel. They had the best of intentions, as they were trying to capture a mythical 'time lady' who was (maybe) causing critical disturbances in time. While illegal, this would have been forgiven if they had found the right person... but kidnapping a 12-year-old girl from an unstable era of the past is NOT OKAY. Over Vivian's objections, they come up with a cunning plan to disguise her as the niece of the Sempitern until they manage to set things straight. But saving time will be a difficult task. They have limited resources, and they can't admit anything they learn to anyone, nor can they patrol all of time on their own.
However they are not entirely unarmed in their quest. They have access to an illegal time gate, a brilliant historian (who does not believe that any of the myths are true, but at least he remembers that the myths exist), and a temperamental 8-year-old mechanical genius. They also have some important hints of what they were going to have done in the future... I mean what they will do in the past... Anyway, they know certain things are going to have been to happen, which is useful information, if you can get your head around it.
AToTC is a good and engaging story, and is well written for the target age group (I'd say ~10 to 16). It is engaging and fast moving, and provides an introduction to good time-travel fiction, which can be rather hard to find in the children's/young adult section. As an adult, I find the beginning to be very engaging, but start to lose some interest towards the end. This might be because the main characters are the driving force in the beginning, but start to lose control over events as the story goes on. Or perhaps because the time travel aspect of the story isn't as well developed as one would hope it to be in an adult SF novel. Either way, these are not a big deal in a children's book, and the story should be quite engaging to younger SF fans. I have also read it four times in the last 20 years, so I obviously find it pretty engaging myself.
AToTC is currently available on Google Books.