The expedition ship 'Horizon' was skimming through the murky interstellar space when it suddenly shuddered under the impact of entering the atmosphere of an unknown planet. Evi sat in the cockpit next to Leo and Iza, watching the blue outline of new land appear on the radar screen. It was the first time each of them had been here - they were only fifteen years old, but they had been selected for the Young Explorers programme because of their extraordinary skills. The planet Xara-7 had been shrouded in mystery for years. Analyses sent back by probes suggested the existence of unusual life forms, but no one had yet set foot there. Evi clutched the transmitter in her hand, her heart beating faster as she paraphrased the instructions from the command centre: - 'First we'll check the oxygen levels and take pictures of the area,' she said, looking at her friends. - 'And then we'll move deeper into the jungle. After just a moment, they were standing on soft, greenish moss, surrounded by trees with glossy leaves. The sky was a strange purple hue. Suddenly Leo, who was carrying the most sensitive scanner, stopped abruptly. - Wait,' he whispered. - 'I've got something strange here. The screen of the device pulsed with a clear signal. A sequential code appeared on the monitor, as if someone - or something - was trying to contact them. Iza raised her head, listening in. Strange sounds surrounded them from all sides - squeaky, yet melodious. - 'I don't think these are ordinary nature sounds,' she stated quietly. Then the ground beneath their feet trembled slightly. The forest lit up with pulsating colours, and the signal in Leo's scanner turned into something resembling a human voice: - Help me... Please... The friends looked at each other in disbelief. They were a long way from Earth, and yet someone - or something - was clearly trying to contact them on this alien planet. After a brief deliberation, they moved cautiously towards the source of the transmission, uncertain of what they would find there. As they approached the dense thickets, all sounds fell silent. An eerie light began to emerge from the centre of the crown of one of the trees.... Evi felt the hair on the back of her neck stand up and her heart pounded like crazy. This thing was waiting for them among the pulsating leaves. And the signal in the scanner flashed one last time.