Bursting right through the four-dimensional travel zone of subspace, Tellurian psionists make an amazing discovery on the other side. Beyond the bounds of subspace, a parallel universe is cruelly ruled by a violent, murderous empire, the Justiciate, where psionists are ruthlessly hunted down and fed to giant eagles. And within the Justiciate are lodged spies and traitors, dedicated to the overthrow – evil agents of the proud Garshan ‘master race’. The arrival of the Tellurian psionists triggers off a truly spectacular space adventure. This is E.E. ‘Doc’ Smith’s last published book; he died in 1965 and Subspace Encounter, the sequel to Subspace Explorers, was not published until 1983. Cover art by Chris Foss.