Something frightening is happening with time. One moment, a time tornado rages through the streets of London, and those caught up in its path vanish without a trace. The next moment a woolly mammoth is seen lumbering along the banks of the River Thames. At the center of these bizarre time warps is a house called Tanglewreck, which is home to eleven-year-old Silver, her bony and bad-tempered aunt, Mrs Rokabye, and a mysterious clock known as the Timekeeper. Silver doesn't understand exactly what the Timekeeper does, but when two sinister figures come looking for it, she knows instinctively that she must guard it with her life.