Nadia brushed her teeth every evening like clockwork: two minutes, flossing, rinsing. Her braces buzzed quietly as she ran the sonic toothbrush along her brackets. That evening the bathroom seemed unnaturally quiet, the mirror steaming only at the edges. Suddenly the vibrations shifted into a rhythm that resembled a whisper, almost a melody. "Don't scrub us harder.... only more thoroughly," came from the very depths of the foam. Nadia froze, then put her phone to the handle and switched on the recorder. It wasn't a video from the internet; it was from her mouth. In the morning, she told Maks, her faithful partner in the biology club, about it. In the school laboratory, Mrs Żarnowska let them look at the plaque under a microscope. On the screen, an entire city could be seen, as if made of sugar and thread. The streets glowed and dozens of spherical bacteria rolled by like a crowd after a concert. "Too many sugary drinks, Nadio?" whispered Maks, seemingly in jest, but his gaze was alert. Suddenly the sample disappeared from the slide, as if a miniature vortex had drawn it in. The glass plate was left empty, and the taste of mint and ozone hung in the air. After class, Nadia returned home with a backpack full of notes and questions. She set the timer for two minutes, unrolled the thread and switched on her toothbrush, as she always did. "If it's a joke, it's a very scientific one," she muttered, starting at the gum line. The whisper returned, even more distinct, like a steady bass under a song. Emalia's guards wait behind the flow; don't scuff, lead softly, for the roads have hidden in the furrows. Nadia leaned over the sink; foam formed into an arrow indicating the drain. Something like a map flashed on the camera lock, a grid of shiny grooves and shortcuts. One line ran straight to where she always forgot to clean. She called to Maks and turned on the speaker so she wouldn't be alone. "If I disappear into the pipes, tell my toothbrush I like it," she joked, but kept her hands steady. She tied the end of the dental floss to the tap and wrapped the other around her wrist. She positioned the brush head just above the drain; the vibration lit up the water like mist beneath the stage. With a hiss, a circle appeared, glistening like enamel under a dentist's lamp. "I can see it," Maks whispered, and curiosity and a shudder sounded in his voice. A silhouette rose from the centre, composed of sugar crystals and sticky rivulets of tile. The shape opened a mouthful of glittering tools, and the mirror fogged into a single, surprisingly legible inscription: "Get in, or we'll get out."