The signal was Thomas's idea.
Not the comms — something simpler, something that used what the chosen ones already had and could not be intercepted by whatever the facility's security was running. Each group had a power that was readable to the others at close range. Katherine's dark element at full spiral. Niall's earth through the floor. Fenix's heat. The specific signatures they had spent months learning to recognize in each other, turned up just enough to say: I am here, I am moving, this is where.
Katherine felt them before she saw them.
One floor above the file room where William was still gathering the last of what they needed, moving through a stairwell that smelled of concrete and cold recycled air, she felt the dark element respond to something — a cluster of signals, distinct and familiar, coming from the same direction.
She pulled at it.
Let the dark element reach.
Five distinct signatures came back.
All of them.
"They're converging," she said to Tierney.
"Where," Tierney said.
Katherine felt the direction of the pull — the specific weight of where the signals were thickest, the center of their gathering.
"Second floor junction," she said. "The wide corridor William mapped. The one that runs east to west through the center of the building."
"That's where the patrol is moving," Fenix said. He had his head slightly tilted, reading the temperature of the building the way he read everything with the fire element — not with his eyes, with the awareness that heat moved and the movement had patterns and the patterns told you where people were. "Three of them. They're not on a circuit anymore. They're converging too."
"On the junction," Katherine said.
"On the junction," Fenix confirmed.
Tierney looked at the stairwell above them.
"Then we need to get there first," she said.
They went up.