The signal had traveled four hundred light-years to reach them, and Commander Yevgenia Solaris had forty-eight hours to decide whether humanity would answer back. In the war room beneath Titan Station, every face around the table was still — the particular stillness of people who understood that history was happening and did not know which side of it they were standing on.
The signal itself was simple. That was what made it so disturbing. Twelve prime numbers, in sequence, then a pause, then twelve more — the same sequence offset by one. Not a language. Not a greeting. A demonstration. We understand mathematics. We know you will recognize this. We are waiting.
"Options," Solaris said.
Dr. Vance, the senior xenolinguist, looked like he hadn't slept in two days because he hadn't. "Respond in kind. Extend the sequence. Show them we received the message and understood the structure." He paused. "Or stay silent. If they've been watching us long enough to know we're here, silence won't buy us safety. It will just tell them we're afraid."
"We are afraid," said Admiral Reyes from the far end of the table.
"Yes," Vance agreed. "The question is whether that fear is more useful as a secret."