“Developing neurosis. I’ll be as plump as a pigeon in a few years.”

“You don’t care?”

Her eyes flashed. “Tonight I want to eat. There’s nothing the matter with that.” She paused. “I’m ravenous, as a matter of fact. A second ago I felt like taking a salad right off that tray.” She gestured toward a waiter wheeling among the tables.

Their food was served promptly. For five minutes Sarah was silent, digging at her enchiladas and tamales. “Care for more?” Tom asked.

“Yeah!” He signaled the waiter and she ordered another round. An appetite was fine, but she was going to turn into a sausage if this kept up. “Got a pencil and paper?” she asked. “I’ve had some insights.”

“I’ll memorize them. Tell me.”

“One. We’re correct to assume that Miriam is evolved from a primate ancestor. She’s too close to us not to be. Two. We therefore need skeletal X rays so that we can determine which primate line is involved. Three. One thing is certain, she and her kind are in some sort of symbiosis with us, otherwise why would they keep themselves hidden? They take something from us we wouldn’t otherwise give.”

“Why does that follow?”

“What else would be their motive for secrecy? And it’s not a matter of being overlooked. It is deliberate. It must also be hard to do. It can’t have been easy to remain undetected for so long.” She paused, ate a couple of bites with birdlike speed. “I wonder what they take from us. I wonder if we’ll find out.”

Tom envied her the clarity of her mind. She had reduced the whole affair to two important questions.

Suddenly she stopped eating. She dropped her fork on the plate and looked up at him, her face pallid. “Let’s get out of here.” Tom obediently paid the bill and they went out into the crowds thronging Eighty-sixth Street. Smoke billowed from chestnut stands, radios under the arms of geeks blared disco music. They passed a Chinese restaurant, a German restaurant, a Greek restaurant. Only when they had rounded the corner onto Second Avenue did the crowds thin.

“I’m going to lose my lunch, I’m afraid.”

“OK, honey.” He wasn’t surprised, the way she had eaten so much spicy food. “Can you make it—” She let go in the gutter. Fortunately, their building was just at the other end of the block and Herb, the late-shift doorman, had seen it happen. He trotted up with a towel in his hand. “Doctor Roberts,” he said in a gruff, surprised voice. “Jeez, you must have got the stomach flu, ma’am.”

Tom was holding her head. He brushed her sweating face with the towel. Cars rushed by three feet away. Pedestrians passed up and down the sidewalk. A fire truck, complete with balancing Dalmatian, roared by. Sarah coughed mightily.