Using its spore-based hub drive, the USS Discovery can jump great distances faster than any warp-faring vessel in Starfleet. To do this, Lieutenant Paul Stamets navigates the ship through the recently revealed mycelial network, a subspace domain Discovery can briefly transit but in which it cannot remain. After responding to a startling distress call from within the network, the Discovery crew find themselves trapped in an inescapable realm where they will surely perish unless their missing mycelial fuel is found or restored. They find a seemingly human man alone and alive inside the network. Is he a Starfleet officer as he claims to be, or an impostor created by alien intruders? -- adapted from back cover