Children of the Star by Sharon Irwin Henry
“Run!” Said Gramma, then disappeared.
River can’t find her; she hadn’t heard from her in three days. Not unusual for Grams to come and go, but it is unusual for her not to call. Every minute sees crazy new technology in Rake—nothing new in an old pattern. But something extraordinary, definitely out of the ordinary, was happening, and it involved Gram. The last thing Gramma said was, Go, go now. Forced to flee without understanding why River does what her Gramma tells her. She runs.
On a faraway planet, in a different dimension, Water lost her grandmother too. In Izaria, an earth-like planet of mind speakers and readers, her grandmother’s presence is no longer with her; not in mind, not in their home. The daily mind chatter with Gran is gone. She hears only silence. And now, she must flee.
“Go find yourself,” their grandma told each of them right before she disappeared.
Neither knew they were lost. The girls are alone and confused. But trusting their grandmother, they run. Secrets are coming out. Everything is about to change, and the adventure is on.