The Great Green Blight

The Empire of Earth was crumbling. Space-liners fell prey to savage phantom crews. A weird, green wave of terror engulfed the Universe. Enslavement of the Empire was near, and only a handful of men could halt the final blow ... a handful of men who could not act—for a single movement would mean their death.
Somewhere aboard the Super Space Liner, Jupiter , a resonant gong sounded three times. Norman Saint Clair started, glanced uneasily about the magnificent lounge. A gray fear gnawed at his vitals. With a sinking heart, he watched the crowd, who had come to see off the passengers, hurry out the port. This was his last chance to get off the ship.
Excuse me, said a voice at his elbow.
Norman Saint Clair spun around, recognized a Universal Lines steward, grinned embarrassedly.
First trip? asked the yellow-clad steward.
The young man nodded.
I wouldn't be too uneasy, sir. We'll pick up our escort this side of the moon. A full ship of the line, sir. We're carrying radium, you know. They wouldn't dare attack a ship of the line. May I see your book, sir?
Norman Saint Clair fumbled in his wallet, handed the steward his book. Since Terra's ships had begun to disappear on the Earth to Jupiter run, the Terrestial Intelligence Service required them of everyone traveling through space. It contained his photograph, a three-dimensional likeness showing a gaunt likeable face crowned by short, crisp blond hair, a photostatic copy of his birth certificate, his description, nationality, business, fingerprints, history.
Satisfied, the steward said: This way, sir, and led him to an acceleration chair at the after end of the lounge. Strap yourself in, sir. We start in a few moments.
The young man eased his lank, six-foot-two frame into the seat, nervously fastened the belt. In spite of the steward's words, he was not reassured. Ship after ship had vanished into the blue. Nor had the vaunted Terrestial Navy or the T.I.S. been able to discover any trace of them thereafter. Somewhere beyond the orbit of Mars their radios crackled and blanked out. Space opened and swallowed them. It was unprecedented. Never before in the history of space travel had anything remotely like it occurred.