Thirteen-year-old Ivy and Ava watch in horror as their friend Brett mysteriously disappears while swimming in the river near their Australian outback farm. The girls soon discover they are suspects in his murder and must endure the taunts and accusations of their schoolmates. Desperate to escape, Ava climbs the massive ring tree on their farm, an ancient landmark believed to be from another time and place. Ivy watches from below as Ava spreads her arms and jumps from the tree...then disappears.

Ivy is heartbroken but finds no comfort at home with a mother who starts drinking in the mornings to forget her own pain. Her only choice is to search for Ava. She stumbles on a clue from the past in an old shack by the river, one that points back to the ring tree where Ava disappeared. The tree is the answer, it says.

The ring tree, Ivy discovers, is a portal to another place and time that she must enter to find the answers she's looking for. In this "other" place she encounters adventure, love, friendship, and unexpected family. But there are dangers lurking, bad people who threaten to harm the ones Ivy loves most.

Quickly, Ivy and her friends must try and find a way back to their own time. But can they go home the same way they came? And what will be waiting for them if they do?