Ships are disappearing in subspace. Traders, rebels, pirates, and even military vessels are losing their way in the Big Nothing that makes space travel possible. Deep-cover agent Sethran Kada joins the investigation after his own navigator, Ciela, barely escapes the void with her mind intact. It soon becomes clear that this subspace trap is more than some natural phenomenon. Seth's search for answers leads him to a brutal penal colony on the brink of revolt, and uncovers a plot to destroy an entire planet. When evidence points to the return of the dangerous subspace entities known as Dyads, Air Command mobilizes to annihilate the threat at any cost. Seth and Ciela pursue a Dyad who has infiltrated a key research complex where they discover that the inexorable subspace peril will not just threaten a single planet. It will mean the end of interstellar travel and destroy their Commonwealth civilization.