They’d heard it the third day after the supply party’s return. Michael still couldn’t believe Theo was gone. Alicia had assured him that it wasn’t his fault, the motherboard had nothing to do with Theo’s death, but still Michael felt responsible, part of a chain of events that had led to the loss of his friend. And the motherboard—the worst part was, Michael had practically forgotten all about it. The day after Theo and the others had departed for the station, Michael had successfully cannibalized an old battery flow control for what he needed. Not a Pion, but enough extra processing power to squeeze out any signal at the top end of the spectrum.

And even if he hadn’t, what was one more processor? Nothing for Theo to die for.

But this signal: 1,432 megahertz. Faint as a whisper, but it was saying something. It nagged at him, its meaning always seeming to dart away from his vision whenever he looked at it. It was digital, a repeating string, and it came and went mysteriously, or so it had appeared, until he’d realized—okay, Elton had realized—that it was coming every ninety minutes, whereupon it would transmit for exactly 242 seconds, then go silent again.

He should have figured that out on his own. There really was no excuse.

And it was growing stronger. Hour by hour, with each cycle, though more so at night. It was like the damn thing was moving straight up the mountain. He’d stopped looking for anything else; he just sat at the panel and counted off the minutes, waiting for the signal to return.

It wasn’t anything natural, not at ninety-minute cycles. It wasn’t a satellite. It wasn’t anything from the battery stack. It wasn’t a lot of things. Michael didn’t know what it was.

Elton was in a mood, too. The ain’t-it-great-to-be-blind Elton that Michael had gotten accustomed to after so many years in the Lighthouse—that Elton was nowhere to be found. In his place sat this dandruffy grump who barely uttered hello. He’d clamp the phones to his head, listening to the signal when it came, pursing his lips and shaking his head, maybe say a thing or two about needing more sleep than he was getting. He could barely be bothered to power up the lights at Second Bell; Michael could have let enough gas build up to blast them all to the moon, and he had the feeling that Elton wouldn’t have said word one about it.

He could have used a bath too. Hell, they both could.