Sarah shook her head. Tom wished he could find some way to lighten Sarah’s mood. “At least she respects your work. She’s reading it.”

“I wish I knew more about her, Tom.”

Behind them Geoff Williams from the blood analysis lab cleared his throat. “I hope I’m not disturbing any lovey-lovey, dears, but I have a problem for you. You got the wrong blood.”

“What wrong blood? What’re you talking about?”

“The blood you gave me marked 00265 A-Blaylock M.? It isn’t human blood.”

“Of course it is. I took it out of that patient right there.” Sarah pointed at the monitor.

Geoff pulled out his computer printout. “You’ll note from the machine’s attempt to analyze it that something is amiss.” The sheet showed the blood’s ID and then a list of zeros where the component values should have been.

“Machine’s on the fritz,” Tom said, turning back to the monitors. “Another roll,” he said. “She’s trying again. Sweet dreams, dearie.”

“No computer problem, Doctor. I ran the test program and then ran other bloods back to back with yours. You did not give me human blood. Whatever this is, the machine cannot analyze it.”

Sarah looked up at him. “You know, I seem to remember a time when blood analysis was done by hand, when it was between a man and his centrifuge.”

“I did it by hand too. Here’s what I found.” He thrust a sheet of numbers at them. “It isn’t a human type as far as I’m concerned. It has a whole extra component of leukocytes, for one thing.”

“Could a human being survive with it?”

“It’s a better blood than ours. Very similar, but more disease resistant. The cellular material is more dense, the plasma less. It would take a strong heart to pump the stuff and there might be some minor capillary clogging, but whoever had it in their veins could forget about sickness if their heart was strong enough to pump the stuff.”

Tom gestured to the screen. “We have a patient right before our eyes who is clearly thriving with it in her veins. Before we draw any further conclusions I think we’d better retest.”

“Of course.”

“It’s her blood,” Sarah snapped. “I didn’t make a mistake.” Tom blinked—he was surprised at the ferocity in her voice.

Geoff must have heard it too, because he paused a moment before speaking again, and then went on very gently. “This cannot have come from that patient, Sarah. If it did then she isn’t a human being. And I can’t believe that.”

“It could be a congenital defect, or a hybrid.”