For All Time by Caroline B. Cooney - Mass Market Paperback

Annie Lockwood is testing Time. She’s traveled through it before, but always at Time’s bidding. Now she is asking Time to take her to the year 1899, when Strat is in Cairo. But Time doesn’t like to be tested. In what feels like a cruel joke, Annie is transported to ancient Egypt, thousands of years before Strat was born — to a world far removed from the one she knows. Meanwhile, in 1899, Strat is photographing the same pyramids that Annie walks among. But while Strat eagerly awaits Annie’s arrival, another visitor arrives: his father, Hiram Stratton, Sr., has come to Egypt to collect his son. 

Powerless, Annie and Strat both look to Time. Can its force, which brought them together once, help them find each other again?