Into the Dim Series by Janet B. Taylor

When fragile, sixteen-year-old Hope Walton loses her mom to an earthquake overseas, her secluded world crumbles. Agreeing to spend the summer in Scotland, Hope discovers that her mother was more than a brilliant academic, but also a member of a secret society of time travelers. Trapped in the twelfth century in the age of Eleanor of Aquitaine, Hope has seventy-two hours to rescue her mother and get back to their own time... moreWhen fragile, sixteen-year-old Hope Walton loses her mom to an earthquake overseas, her secluded world crumbles. Agreeing to spend the summer in Scotland, Hope discovers that her mother was more than a brilliant academic, but also a member of a secret society of time travelers. Trapped in the twelfth century in the age of Eleanor of Aquitaine, Hope has seventy-two hours to rescue her mother and get back to their own time. Along the way, her path collides with that of a mysterious boy who could be vital to her mission . . . or the key to Hope’s undoing. less

For the first time in her life, Hope Walton has friends . . . and a (maybe) boyfriend. She’s a Viator, a member of a long line of time-traveling ancestors. When the Viators learn of a plan to steal a dangerous device from the inventor Nikola Tesla, only a race into the past can save the natural timeline from utter destruction. Navigating the glitterati of The Gilded Age in 1895 New York City, Hope and her crew will discover that high society can be as deadly as it is beautiful.