K-Girls Plus One
The second book in the "Kylemore Abbey School" series by author and K-Girl, Lydia Little.
"Would you let someone die if you could prevent it?
Alice and Ruth's special bond permits them to explore the days of Kylemore's past, when their school was a Victorian estate owned by the ill-fated Henry family.
But such adventuring has its consequences.
With the arrival of an illusive matron, two-faced twins and the mystery of a new haunting, life in second year gets a lot more complicated.
Of one thing Alice is sure: being K-Girls is never dull, especially when you can time travel!"