As the planet gleamed in his viewport, Sallman Ken could not believe that such a bleak and icy globe could have produced intelligent life. Yet when the expedition had sent in unmanned landers, that was what it had found. Some sort of native alien, surviving on the barren planet. But Sallman and his team were not the first to make contact. Smugglers from his own planet had begun trading with the natives for a new and virulent narcotic - the most dangerous drug in the universe. Now Sallman would have to find out how he could survive on a planet so cold that sulphur was solid and water was liquid - and how to stop the source of the deadly drug!

Mesklin is a vast, inhospitable, disc-shaped planet, so cold that its oceans are liquid methane and its snows are frozen ammonia. It is a world spinning dizzyingly, a world where gravity can be a crushing 700 times greater than Earth's, a world too hostile for human explorers. But the planet holds secrets of inestimable value, and an unmanned probe that has crashed close to one of its poles must be recovered. Only the Mesklinites, the small creatures so bizarrely adapted to their harsh environment, can help. And so Barlennan, the resourceful and courageous captain of the Mesklinite ship Bree, sets out on an heroic and appalling journey into the terrible unknown. For him and his people, the prize to be gained is as great as that for mankind... Hal Clement's MISSION OF GRAVITY is universally regarded as one of the most important and best loved novels in the genre. The remarkable and sympathetic depiction of an alien species and the plausible and scientifically based realisation of the strange world they inhabit make it a major landmark in the history of hard SF.

Shrouded in eternal gloom by its own thick atmosphere, Tenebra was a hostile planet: a place of crushing gravity, 370-degree temperatures, a constantly shifting crust and giant drifting raindrops. Uncompromising - yet there was life, intelligent life on Tenebra. For more than twenty years, Earth scientists had studied the natives from an orbiting laboratory... and had even found a way to train and educate a few of them.

The planet was an enigma—and its solution was death!

Time was running out for Bob Kinnaird. Without much warning, the Hunter - the green protoplasmic alien that lived inside him and cured all his ills - had suddenly become his destroyer. Day by day Bob grew weaker and weaker, but only specialists from the Hunter's distant world would know what was wrong with him and, more importantly, how to save him. But the only way searchers from his planet could find him was to locate his missing spaceship . . . a spaceship that had crashed beneath the ocean years before, its location still very much a mystery. Once again leading an investigation against time - as he had done so many years before - the Hunter knew he had to find comrades and find them fast . . . before someone murdered his best friend.

Stranded on an alien planet, light years from home, wandering from blistering heat to searing cold, Nils Kruger was not a happy man. So when he met another being - even though it wasn't human - things seemed to be looking up. The alien might be helpless, or it might be dangerous, but one thing was for sure - they stood a better chance for survival if they worked together. But as the two creatures overcame their mutual suspicion, as they worked together, as the language barrier was broken down, Nils came to a terrifying conclusion - this alien was more intelligent than a human. And to it, Nils was the alien

Hal Clement, the dean of hard science fiction, has written a new planetary adventure in the tradition of his classic Mission of Gravity. It is the kind of story that made his reputation as a meticulous designer of otherworldly settings that are utterly convincing because they are constructed from the ground up using established principles of orbital mechanics, geology, chemistry, biology, and other sciences. Kainui is one of a pair of double planets circling a pair of binary stars. Mike Hoani has come there to study the language of the colonists, to analyze its evolution in the years since settlement. But Kainui is an ocean planet. Although settled by Polynesians, it is anything but a tropical paradise. The ocean is 1,700 miles deep, with no solid ground anywhere. The population is scattered in cities on floating artificial islands with no fixed locations. The atmosphere isn't breathable, and lightning, waterspouts, and tsunamis are constant. Out on the great planetary ocean, self-sufficiency is crucial, and far from any floating city, on a small working-family ship, anything can happen. There are, for instance, pirates. Mike's academic research turns into an exotic nautical adventure unlike anything he could have imagined.