“Say no more, sir!” said Tony, saluting me enthusiastically. He scrambled back up the ladder into the cab, all but exploding with pleasure and nervous energy. This was his moment, his great chance, come round at last, and he couldn’t wait to get under way. I’d rather been counting on that. Anyone just a bit less enthusiastic might have asked a whole bunch of awkward questions, to which I didn’t have any good answers. I felt a bit guilty at taking advantage of Tony, but only a bit. I had too many other things to feel guilty about. I needed the warrior called Deathstalker, the family needed him, and that was all that mattered. Molly and I followed Tony up the narrow steel ladder and into the surprisingly spacious cab. Molly and I stood well back as Tony hurried from one long steel lever to another, throwing them back and forth with infectious enthusiasm and good cheer. Nothing like watching an enthusiast show off at what he does best. He leaned forward to check a row of old-fashioned gauges on the main bulkhead, and tapped a few with a forefinger before turning around to smile brightly.

“I always maintain a good working head of pressure,” he said proudly. “Partly because it’s good for the boiler, partly just in case the call should ever come . . . Allow me a few minutes to shovel in some more fuel, and then we can be on our way! Oh yes!”

“Where are the tracks?” said Molly, leaning dangerously far over the side of the cab before I pulled her back.

“As I understand it, there aren’t any,” I said. “Ivor travels in time, not space.” I looked at Tony. “You can leave the carriages behind. We won’t be needing them.”

His face fell. “But . . . they’re very comfortable! Downright cosy, in fact. Polish the brass every day, I do!”

“Nevertheless,” I said firmly.

Tony pouted, and then went back to unhitch the carriages. I took a look at the various gauges, but they meant nothing to me. And yet, I could feel something . . . a sense of pressure building, of controlled power gathering itself. Standing in Ivor’s cab was like standing in the mouth of a great beast as it finally came awake. Tony jumped back into the cab, opened the tender door, and started shovelling what looked very like coal into the open chamber. Molly and I watched for a while.

“Excuse me,” said Molly, “but . . . how exactly does building up a head of steam help us to travel in time?”

“Oh, this isn’t coal, miss,” said Tony, shovelling energetically. “This is crystallised tachyons.”

Molly’s scowl deepened. “But . . . tachyons are particles that can’t travel any slower than the speed of light, so . . .”