The Archaeologist of Lost Worlds: Earth Reborn Book One

On a frozen dig north of Yakutsk, Maya Okafor frees a gray stone disc from the permafrost. It's carved with a spiral crossed by a bar, it's lying where it has no business being, and when she brushes the symbol, it warms in her bare hand.

That night, masked strangers storm the camp. Her aunt Nadia admits she's been hiding what she knows and orders Maya to run. Out on the river ice, the disc flares, and Maya falls through time.

An Ice Age steppe forty thousand winters ago. A harbor city on land that now lies under the North Sea. A rainforest village and a desert city of canals. Every world shows Maya a different way people take care of one another, and every jump brings the Custodians an ancient order that wants the stone back, and the boy, Elias, they sent to find her.

To get home, Maya has to learn what the stone is, who made it, and why its symbol turns up in her mother's notebooks.