Chosen Ones (The Aedyn Chronicles)

'Engaging Fantasy'--- Kirkus Review The land of Aedyn is a paradise beyond all imagining. But when this paradise falls, strangers from another world must be called to fight for the truth. Peter and Julia never suspected that a trip to their grandparents' home in Oxford would contain anything out of the ordinary ... That was before Julia stumbled upon a mysterious garden that shone on moonless nights. It was no accident that she fell into the pool, pulling her brother along with her, but now they're lost in a strange new world and they don't know whom they can trust. Should they believe the mysterious, hooded lords? The ancient monk who appears only when least expected? Or the silent slaves who have a dark secret of their own? In a world inhabited by strange beasts and peculiar whisperings, two children called from another world will have to discover who they truly are, fighting desperate battles within themselves before they can lead the great revolution.