Angleton shakes his head. "The Squadron was based in Filton and Heathrow, flying in British Airways livery—the aircraft movements were described as charter flights, and they wore the hull numbers of BA airframes that were currently undergoing maintenance. They flew one mission a week, departing west over the Atlantic. They refueled from a VC-10 tanker, then the supercargo would open a gate and they'd make a high-speed run across the dead plateau before reopening the gate home and landing at Filton for decontamination and exorcism. It's all in CODICIL BLACK SKULL. Which you are cleared to read, incidentally."

I shake myself and take a deep breath. "Let me get this straight. You're telling me that the RAF has a squadron of black Concordes which they currently keep in a hangar at RAF Cosford? Helen Langhorn was a former Soviet spy who, by a happy accident—for her employers—was in a position to poke around them? Which she did, with results that . . ." I shudder, remembering again: a purple flash, face shrinking and crumpling in on itself around the harsh lines of her skull. "And now the Thirteenth Directorate are sniffing round?"

"Very good! We'll make a professional paranoid out of you one of these days." Angleton nods, grudging approval.

"Concorde." I do a double take. "But they've been retired, right?"

"That put a crimp on the cover story, certainly. These days they fly only at night, described as American B-1Bs if anyone asks. A big bomber with four engines and afterburners is a much flimsier cover, and the plane spotters and conspiracy theorists keep the Plumbers busy, but we cannot neglect the watch on the dead plateau. If the thing in the pyramid should stir—" He makes an abrupt cutting gesture with the edge of one hand.

"Dead plateau? Thing in the pyramid?" I've got no idea what he's referring to, but it sounds ominous.

"You've been through a gate to elsewhere." I remember a world in the grip of fimbulwinter, where the rivers of liquid air ran down through valleys of ice beneath a moon carved with the likeness of Hitler's face. "There are other, more permanent, elsewheres. Some of them we must monitor continuously. That world . . . pray you never see it, boy, and pray that the sleeping god in the pyramid never awakens."

I tilt my head from side to side, trying to spill the invisible goop that's clogging up my mind. Thinking in here is difficult, as if the air, hazy with the congealed fumes of state secrets, is impeding my ability to reason—

"Boss. Why are you here? Everyone thinks you've gone missing, AWOL with no forwarding address."

Angleton grins skeletally. "Good. Let's keep it that way."