The first ever interstellar spacecraft Sagan has been silently cruising through the blackness of space for 128 years towards mankind's first colonisation attempt in Epsilon Centauri. The Halfway event is fast approaching and the aging spinship will soon start decelerating the rest of the way to Aquanis, the ocean world that is promised to the 20,000 passengers that live inside its halls.

Julian and Rachel have lived all their lives bearing the cruel fate of the middle generation, born too late to have seen the Earth and too early to witness Aquanis. There is no way out of their floating prison but people have kept disappearing over the years. When Rachel finds out her brother is the last person to go missing, both teenagers will stop at nothing until they discover what happened to him.

What they uncover is a clandestine truth that has remained concealed since the Sagan left the Earth, a secret that will put everyone in danger and jeopardise the fate of the ship and the mission. The silent war that was happening in the shadows of the ship is reignited and there will be no coming back from it.