Here are five adventures in planetary exploration capable of orbit the most Earthbound reader. You will find yourself embroiled in interplanetary riddles as pioneer space rovers Penton and Blake pit their wits against five alien races. Into the fray come an array of otherworld creatures - invisible imps, super-evolved blobs, and an amazing tribe of human chameleons. Watch, for the instance, how the adventures from Earth use their cunning to escape death from the 'spreading shleath' who ooze their unpleasant slime into every crack and crevice of the planet. (First published in 1966)