The Masked World by Jack Williamson - The planet hid itself from the Earthmen—and what lay behind the mask was fierce and deadly!

The planet wore a mask.

At ten million miles, it was a sullen yellow eye. At one million, a scarred and evil leer. Outside the smoking circle our landing-jets had sterilized, it was a hideous veil of hairy black tentacles and huge sallow blooms, hiding the riddle of its sinister genes.

On most worlds that we astronauts have found, the life is vaguely like our own. Similar nucleotides are linked along similar helical chains of DNA, carrying similar genetic messages. A similar process replicates the chains when the cells divide, to carry the complex blue-prints for a particular root or eye or wing accurately down across ten thousand generations.

But even the genes were different here—enormously complicated. Here the simplest-seeming weed had more and longer chains of DNA than anything we had seen before. What was their message?

We had come to read it, with our new genetic micro-probe. A hundred precious tons of microscopic electronic gear, it was designed to observe and manipulate the smallest units of life. It could reach even those strange genes.

That was our mission.

Ours was the seventh survey ship to approach the planet. Six before us had been lost without trace. We were to find out why.

Our pilot was Lance Llandark. A lean hard man, silent and cold as the gray-cased micro-probe. We hated him—until someone learned why he had volunteered to come.

His wife had been pilot of the ship before us. When we knew that, we began to hear the hidden tension in his tired voice, monotonously calling on every band: "Come in, Six.... Come in Six...."

Six never came in.