The Nyrian Transmission

After three hundred years of travelling across the expanse, it finally reached Earth. The first signal was brief, and once deciphered consisted of three words: "Message to follow". The second took longer to decode, and was a detailed tutorial of an alien language. In the third message, the Nyrians introduced themselves. In response, humanity sent two ships: The Concurrent mission travelled three hundred lightyears to see who was still there. The Response team folded both space and time to find out who originally sent it. Both were unprepared for what they found.