The Angeluscustos and the Wonderful Waterfall — Elizabeth Anderson

With the prince imprisoned, a usurper on the throne, and enemies at the border, the kingdom of Serenia calls out for help. It arrives in the form of angeluscustos, guardians honor bound to help Serenia in time of dire need â€" and surprisingly young ones. Four siblings find themselves suddenly thrust into a world on the brink of war and amazingly in possession of magical powers gifted to them by the God who set them on their quest to make things right. But when one of them is captured and injured in the process, and the children are separated, they begin to fear they will not succeed. And how will they get home?