Riders of the Lightning Storm (Horse Passages #1)
Twins Carl and Meagan Cadet are the youngest herders in the Federation. Their parents and younger sister were abducted by the enigmatic Raiders, and now they are alone with their horses. Aware of the dangers, they continue to herd the horses that somehow open passages between planets.
They are on Tauii 3 when Luke Jeffries arrives on the scene with his herd. Luke and Meagan are pulled together as they come to grips with their losses. When raiders capture Meagan and Luke, they become prisoners working in mines on an isolated asteroid. Escape seems impossible, but they encourage each other to keep up the hope even as they begin to fall in love.
But before they can escape, they must somehow unlock the mystery of the horse passages.