The city of Lunaris lay beneath a transparent dome on the Silver Sea of the Moon. The lights of skyscrapers reflected in the black dust, and robotic helpers flitted among the gleaming alleys. The unusual city was home to three friends: Lara, a daring drone programmer; Ivo, the captain of a youth exploration team; and Miko, a builder of extraordinary machines. Their lives went on between school and fascinating projects in the lab under the dome. One day, through the window of the lab, Lara saw something disturbing. On the horizon, beyond the dome, a grey mist was drifting. It was impossible! There is no weather on the moon, and certainly not fog. "Look!" - she called out. Ivo and Miko approached the panoramic window. The fog was moving slowly, almost as if it had a purpose of its own. When the lights at the western end of the city went out, their communicators beeped with alarm. Someone or something had cut the power to the research zone. The friends quickly picked up the necessary equipment: Ivo packed the atmosphere scanner, Lara grabbed her upgraded drones and Miko the armour built from nanofibres. As they left the lab, they saw the fog begin to pour into the dome through a small gap in the airlock. A quiet buzzing sounded in the air, as if someone or something was approaching from hiding. The friends looked at each other - they needed to discover what was hidden in the mist before it engulfed the entire city. As their footsteps echoed through the quiet corridors, suddenly the door to the service area slammed shut with a clatter, and a strange shadow appeared in the semi-darkness in front of them. They held their breath and moved forward, not knowing what awaited them on the other side....