"There's my missing passenger," said the doctor.
The child looked soberly about. She saw him. "Excuse me," she said very politely. "Is this the way I'm supposed to go?"
"Through that door," said the doctor gruffly.
"Thank you," said the little girl. She followed his direction. She vanished through the door. It closed.
There came a deep, droning sound, which was the interplanetary drive of the Star Queen, building up that directional stress in space which had seemed such a triumph when it was first contrived. The ship swung gently. It would be turning out from orbit around Altaira. It swung again. The doctor knew that its astrogators were feeling for the incredibly exact pointing of its nose toward the next port which modern commercial ship operation required. An error of fractional seconds of arc would mean valuable time lost in making port some ten light-years of distance away. The drive droned and droned, building up velocity while the ship's aiming was refined and re-refined.
The drive cut off abruptly. Jensen turned white.
The doctor said impatiently, "There's nothing wrong. Probably a message or a report should have been beamed down to the planet and somebody forgot. We'll go on in a minute."
But Jensen stood frozen. He was very pale. The interplanetary drive stayed off. Thirty seconds. A minute. Jensen swallowed audibly. Two minutes. Three.
The steady, monotonous drone began again. It continued interminably, as if while it was off the ship's head had swung wide of its destination and the whole business of lining up for a jump in overdrive had to be done all over again.
Then there came that "Ping-g-g-g!" and the sensation of spiral fall which meant overdrive. The droning ceased.
Jensen breathed again. The ship's doctor looked at him sharply. Jensen had been taut. Now the tensions had left his body, but he looked as if he were going to shiver. Instead, he mopped a suddenly streaming forehead.
"I think," said Jensen in a strange voice, "that I'll have a drink. Or several. Will you join me?"
Nordenfeld searched his face. A ship's doctor has many duties in space. Passengers can have many things wrong with them, and in the absolute isolation of overdrive they can be remarkably affected by each other.
"I'll be at the fourth-level bar in twenty minutes," said Nordenfeld. "Can you wait that long?"
"I probably won't wait to have a drink," said Jensen. "But I'll be there."
The doctor nodded curtly. He went away. He made no guesses, though he'd just observed the new passengers carefully and was fully aware of the strict health regulations that affect space travel. As a physician he knew that the most deadly thing in the universe was chlorophage and that the planet Kamerun was only one solar system away. It had been a stop for the Star Queen until four years ago. He puzzled over Jensen's tenseness and the relief he'd displayed when the overdrive field came on. But he didn't guess. Chlorophage didn't enter his mind.
Not until later.
He saw the little girl who'd come out of the airlock last of all the passengers. She sat on a sofa as if someone had told her to wait there until something or other was arranged. Doctor Nordenfeld barely glanced at her. He'd known Jensen for a considerable time. Jensen had been a passenger on the Star Queen half a dozen times, and he shouldn't have been upset by the temporary stoppage of an interplanetary drive. Nordenfeld divided people into two classes, those who were not and those who were worth talking to. There weren't many of the latter. Jensen was.
He filed away the health slips. Then, thinking of Jensen's pallor, he asked what had happened to make the Star Queen interrupt her slow-speed drive away from orbit around Altaira.
The purser told him. But the purser was fussily concerned because there were so many extra passengers from Altaira. He might not be able to take on the expected number of passengers at the next stop-over point. It would be bad business to have to refuse passengers! It would give the space line a bad name.
Then the air officer stopped Nordenfeld as he was about to join Jensen in the fourth-level bar. It was time for a medical inspection of the quarter-acre of Banthyan jungle which purified and renewed the air of the ship. Nordenfeld was expected to check the complex ecological system of the air room. Specifically, he was expected to look for and identify any patches of colorlessness appearing on the foliage of the jungle plants the Star Queen carried through space.
The air officer was discreet and Nordenfeld was silent about the ultimate reason for the inspection. Nobody liked to think about it. But if a particular kind of bleaching appeared, as if the chlorophyll of the leaves were being devoured by something too small to be seen by an optical microscope—why, that would be chlorophage. It would also be a death sentence for the Star Queen and everybody in her.
But the jungle passed medical inspection. The plants grew lushly in soil which periodically was flushed with hydroponic solution and then drained away again. The UV lamps were properly distributed and the different quarters of the air room were alternately lighted and darkened. And there were no colorless patches. A steady wind blew through the air room and had its excess moisture and unpleasing smells wrung out before it recirculated through the ship. Doctor Nordenfeld authorized the trimming of some liana-like growths which were developing woody tissue at the expense of leaves.
The air officer also told him about the reason for the turning off of the interplanetary drive. He considered it a very curious happening.
The doctor left the air room and passed the place where the little girl—the last passenger to board the Star Queen—waited patiently for somebody to arrange something. Doctor Nordenfeld took a lift to the fourth level and went into the bar where Jensen should be waiting.
He was. He had an empty glass before him. Nordenfeld sat down and dialed for a drink. He had an indefinite feeling that something was wrong, but he couldn't put his finger on it. There are always things going wrong for a ship's doctor, though. There are so many demands on his patience that he is usually short of it.
Jensen watched him sip at his drink.
"A bad day?" he asked. He'd gotten over his own tension.
Nordenfeld shrugged, but his scowl deepened. "There are a lot of new passengers." He realized that he was trying to explain his feelings to himself. "They'll come to me feeling miserable. I have to tell each one that if they feel heavy and depressed, it may be the gravity-constant of the ship, which is greater than their home planet. If they feel light-headed and giddy, it may be because the gravity-constant of the ship is less than they're used to. But it doesn't make them feel better, so they come back for a second assurance. I'll be overwhelmed with such complaints within two hours."
Jensen waited. Then he said casually—too casually, "Does anybody ever suspect chlorophage?"
"No," said Nordenfeld shortly.
Jensen fidgeted. He sipped. Then he said, "What's the news from Kamerun, anyhow?"
"There isn't any," said Nordenfeld. "Naturally! Why ask?"
"I just wondered," said Jensen. After a moment: "What was the last news?"
"There hasn't been a message from Kamerun in two years," said Nordenfeld curtly. "There's no sign of anything green anywhere on the planet. It's considered to be—uninhabited."
Jensen licked his lips. "That's what I understood. Yes."
Nordenfeld drank half his drink and said unpleasantly, "There were thirty million people on Kamerun when the chlorophage appeared. At first it was apparently a virus which fed on the chlorophyll of plants. They died. Then it was discovered that it could also feed on hemoglobin, which is chemically close to chlorophyll. Hemoglobin is the red coloring matter of the blood. When the virus consumed it, people began to die. Kamerun doctors found that the chlorophage virus was transmitted by contact, by inhalation, by ingestion. It traveled as dust particles and on the feet of insects, and it was in drinking water and the air one breathed. The doctors on Kamerun warned spaceships off and the Patrol put a quarantine fleet in orbit around it to keep anybody from leaving. And nobody left. And everybody died. And so did every living thing that had chlorophyll in its leaves or hemoglobin in its blood, or that needed plant or animal tissues to feed on. There's not a person left alive on Kamerun, nor an animal or bird or insect, nor a fish nor a tree, or plant or weed or blade of grass. There's no longer a quarantine fleet there. Nobody'll go there and there's nobody left to leave. But there are beacon satellites to record any calls and to warn any fool against landing. If the chlorophage got loose and was carried about by spaceships, it could kill the other forty billion humans in the galaxy, together with every green plant or animal with hemoglobin in its blood."