Free Storm Prey by John Sandford

never knew quite what you’d get when you made the first cut. Sometimes it was saddle leather, sometimes tissue paper. Older people often had papery skin, and so did the young, though it was different.
    Cutting into the twins was like cutting into a piece of Brie; Weather had noted that in earlier operations and no longer really paid attention to it. There was almost no separation between scalp and bone. She cut the first jigsaw pattern, got one little arterial bleeder, burned it, then slowly peeled the skin away from the incision. The room was suffused with the scent of burning blood, not unlike the smell of burning hair.
    Her first part had taken twenty minutes.
    She hadn’t done much, but at the same time, she thought, everything: they were under way. They could still turn back, but the bone-cutter was right there, with his custom surgical jigs. Once they were in, turning back would be more complicated.
    “I’m out,” she said.
    “Looks good,” Maret said. “Perfect.”

    SEPARATING THE TWINS was not a matter of simply cutting bone and then snapping them apart. The venous drainage inside the skull had to be carefully managed, or blood pressure would build in the babies’ skulls and damage their brains, and likely kill them.
    The brains themselves were covered by a sheath of thin, tough tissue called the dura mater, which acted like a seal between the brain and the skull, and channeled the blood away from the brain. The dura mater, in most places, was thick enough that it could actually be split apart—like pulling a self-stick stamp off its backing—leaving each brain covered with a sheet of dura mater.
    However, the imaging had shown that there were a number of veins that penetrated the dura mater, and rather than returning to the original twin, instead drained to the other twin. Those veins had to be tied off, and, in the case of several of the larger ones, redirected and spliced into other veins that drained to the appropriate twin.
    To get inside, Hanson would fit a custom-made jig, or template, around the join between the twins’ skulls. During the course of the operation, he would cut out a ring of bone, with what amounted to a tiny electric jigsaw. When the twins were taken apart, the holes in their skulls should be precisely the shape and thickness of pre-made skull pieces made of a plastic composite material.
    Before that could happen, Hanson had to take out the bone, and then Maret, a neurosurgeon, and a couple of associates, would probe the physiology right at the brain, to make sure there was no entanglement of the brains themselves. Imaging said that there was not; if there had been, the shorter operation would have been impossible. When they’d confirmed the imaging, and that the dura mater stretched across the defect, they would begin separating the tissue, and splicing veins.
    Weather’s surgical tech started giggling at the scrub sink and said, “I was so scared. I did three little things and I was completely freaked out.”
    “I was a little nervous myself,” Weather said. “Are you okay?”
    “Oh, sure. It’s just that everybody’s up there watching. Everybody important. What if I dropped a scalpel on your foot?”
    “I’d have to have you killed,” Weather said.
    The nurse started giggling again, and it was infectious, and Weather started, though it was unsurgeon-like. They’d just stopped when Weather said, “Couldn’t you see it? Sticking out from between a couple toes? What would I say? Ouch?”
    They started again.
     
     
    WEATHER STRIPPED out of the sterile gown, head-covering, shoe covers, and surgical gloves, and tossed it all into disposal baskets and walked down to the lounge where the twins’ parents were waiting.
    They both stood up when Weather walked in, and she smiled and said, “It’s going. I made the first incisions, and Hanson is getting started on the entry.”
    “How are the girls?” Larry asked.
    “They’re strong. Sara’s heart is fine. This next