Deadman Switch: Timothy Zahn

Solitaire: a unique ring of heavy-metal moons. For decades after its discovery an unexplained 'effect sphere' kept all hyperships away from a metal-hungry galaxy's most tantalising prize. Until a research ship penetrated the Cloud entirely by accident - when the man at the helm died of a heart attack just before entering the sphere. For the first time a ship's hyperdrive did not fail as it approached Solitaire. For the researchers, the difficulty came when it was time to leave...Now every ship heading for the Ring Mines carries two death-row felons - one for entry, the other for exit. It's as a bizarre a method as the effect it counters, but it works...until the hero of Deadman Switch discovers that oneof his condemned criminals isn't guilty...Cover art by David Mattingly.