On the Threshold - Elaine Prouty;Christian Horning;Jacob Romeo Lecuyer

Hali and Wren are the highly unusual children of two brilliant scientists-one human, one alien. Due to Hali's physical appearance and Wren's hypersensitivity, they grow up in off-grid isolation, hidden from the human world.

Meanwhile back on their birth planet of Eidelon, True-King Volkar's strapping and arrogant son-is growing up too. His father's kingdom now faces civil war and True is tasked with bringing traitors to justice. Confident in his purpose, he remains unaware of the darkness within his own country. Like Hali and Wren, he has been raised in sheltered oblivion.

Worldviews collide when Hali and Wren reach their teenage years. Following the destruction of their farm and the death of their parents, the siblings flee Earth with Alexis, an interplanetary wise woman known as "The Key." Upon returning to Eidelon they must adapt quickly in a world they do not fully comprehend. Pulled in opposite directions during an increasingly violent insurrection, Hali and Wren soon find themselves on the threshold of entirely new destinies.

On the Threshold is the first book in The Key Trilogy, a YA fantasy adventure.