The Violet Flash
"Twelve-year-old Ches Cholmondeley saw his sister disappear. Now there are more mysteries: atomic clocks have lost a second, resulting in bizarre events from dropped casseroles to plane crashes. What's a brother to do? Figure out a way to get his sister back, of course. But the situation is dire. Someone is stealing time, and if the thief isn't stopped, the world will end. And when he does learn how to mend the umbrella, Ches is torn, knowing that the very deed that will save the world might also keep Chelsea from ever returning to it"--Publisher's website.