First Contact Protocol

Dr. Cass Moreau had descended to the hadal zone four times before. Each time, the submarine's lights illuminated the same grey-black void, the same impossible pressures, the same absence of light that made her feel not like a scientist but like an intruder in a place that had been sealed for reasons she didn't fully understand.

The fifth descent was different.

The signal had started eleven days ago. Station Coordinator Reyes had flagged it at 0347—a sequence of sixty-four pulses in a frequency that the station's instruments were not designed to receive, which was precisely why they had received it. An artifact of the sensor arrays' harmonic response to pressures at depth, the engineering team had said. Background noise given structure by confirmation bias, the psychologist had said.

The signal repeated every forty-seven minutes, four seconds.

It had not varied by a single pulse in eleven days.

Moreau sat in the observation bubble and watched the sonar return its slow green sweep across the topography of the bottom. Three kilometers below the station floor, the Moreau Trench—named for a great-uncle she had met twice—dropped another eight thousand meters into a darkness that instruments described in numbers but that no framework of human experience could adequately contain.

The signal was coming from the bottom.

Not the bottom of the Trench. The bottom of the thing that the Trench was itself descending into.

She pressed the intercom. "Reyes. I want to initiate a dive."

There was a pause that she interpreted correctly as the sound of a man deciding how honest to be.

"Cass," he said finally. "We've talked about this."

"I know. I want to do it anyway."