Free Skybuilders (Sorcery and Science Book 4) by Ella Summers

remove the door and had engineered an avalanche of office furniture.
    “Idiots,” grunted Silas, and even he looked amused.
    Leonidas opened the door again and took one step into the next room. It was nearly identical in size to the first room. The only difference was the glass door set inside a glass wall at the far end.
    “Ok. By the time the assassins dug themselves out, Marin and the boys had retreated to the third and final room.” He pointed toward the glass wall. “As you can see, that wall is not much of a deterrent to an attacking party. Not only would bullets pass relatively unhindered through the glass, its transparency does not allow one much privacy for setting up clever traps. Knowing Marin, she would have filled this second room with a gas that made any encroaching aggressors pass out.”
    He crouched down to tap two punctures in the floor. They appeared to have been made by two heavy-duty blades. Maybe a Wing knife or even a Crescent sword, which had once been the weapon of choice for members of the Crescent Order.
    “The first two assassins rushed in and abruptly tripped and passed out, their drawn blades denting the floor. At which point, the rest of the assassins withdrew back to the first room.”
    Leonidas took two steps back, then turned toward a door on the side wall. He opened it up into another lab, the exact mirror image of the one they’d been investigating. Leonidas walked through the empty lab until he reached the back window, Ariella and Silas following closely behind.
    “Some of the assassins went this way.” He fingered the window handle. “They climbed out through here and shimmied over to the window of the adjacent lab.”
    Leonidas retraced his steps, leading them back through the rooms until they stood before the glass wall. He paused to stare for a moment, then passed through the door and continued on toward the back window.
    “Marin must have seen the assassins coming from the outside,” he said, biting his lip in thought.
    He pressed a button on the wall. Water and soap squirted out from all directions, covering the outside pane. Large wiping blades swept across the surface, cleaning the fluids away.
    So, that’s how the Helleans cleaned the outside windows of their floating cities. Ariella had often wondered. Considering the substantial drop down into the middle of the ocean, she couldn’t imagine anyone venturing outside, clinging to the walls as they cleaned.
    “Interesting,” Leonidas commented, leaning so close to the window that his nose nearly pressed against it.
    “Black residue?” Ariella wondered, coming in for a closer look at the dark particles sprinkled across the glass. They were nearly invisible.
    Leonidas considered the residue briefly, then broke into a smile. “Marin. She mixed up some concoction and squirted them with it. I’d imagine something that burns. She likes that sort of thing.”
    Ariella nodded. That sounded just like Marin.
    Leonidas pushed once on a square metal panel mounted to the wall, and it popped out. Inside was a compartment just large enough for a few spoonfuls of soap — or Marin’s burning solution. It seemed to be what fed the window cleaning sprinklers. That’s how Marin had gotten her spray to its targets.
    “During this time, the assassins past the glass door must have been trying to distract Marin and the boys.”
    Leonidas pointed at the desktop. Five bullet-sized craters had been filled in. It was a clean repair job, but still noticeable in the harsh direct sunlight streaming in through the window. Leonidas ran to the glass wall. Ariella looked over his shoulder as his finger passed over another five patched holes.
    “The assassins took five single shots into the room. They didn’t want to risk killing their targets, which means their contract stipulates that they bring them in alive,” he decided.
    “Good,” Silas said. “It means we can still save them.”
    Leonidas turned and darted once again through the