She hesitated slightly before putting her arms about Mal’s waist, feeling the new hardness of four years of exercise, the breadth of her shoulders now they’d filled out. Forty-nine per cent of her brain insisted she get off the moped and demand answers. But the rest was just shrieking out its excitement and didn’t care when Mal revved the moped and cut across the nose of a taxi.

So you met the Nissa. “Is that what Stig is?” Lee shouted above the slipstream.

“Right,” Mal yelled back. “They found me. Recruited me because they had work to do here. Regretting it, I reckon.”

“Four weeks?” Lee shouted.

“What?”

“You’ve been back four weeks?”

There was a change in the set of Mal’s shoulders, achingly familiar: the girl who couldn’t quite close the gap between herself and her emotions.

“I wanted to call earlier, but…” And there was no end to that sentence.

“It’s okay,” Lee said. And though surely this wasn’t the time or the place, she added, “I slept with other people.” Only two in four years, only one of them more than once. It had felt like cheating, even with Mal consigned to “presumed dead.”

“Don’t care!” Mal shot back. “And I’m sorry!”

“Not your fault. You didn’t go on purpose!” Did you? But Lee felt that any ill-feeling, guilt or worry she could generate was being left behind in their wake.

“No, sorry for the trouble, now. Sorry for bringing this to you. My fault!”

Lee leant against her, cheek to Mal’s hard shoulder, and if there were tears of sadness or joy, their breakneck progress whirled those away as well.

She’d had no idea where Mal was going, but she was guessing at some secret den, a speakeasy, a criminal dive, or perhaps out of London altogether. Just out until there was no city penning them in, somewhere where there were trees, open space, rolling fields. Not the august frontage of the Natural History Museum, in short.

“Um, what?” she asked, when Mal had brought the overstressed moped to a shuddering stop. “Seriously?”

“That’s where the show’s at,” Mal said, and grinned. It was a strained one, though. That pallor was not just life in a cold climate. “They’re in there, right now, the Nissa. They’re doing their thing, trying to save the world. Worlds.”

“And old Richard Owen just happened to build the museum on a…magical portal?” Lee demanded.

“Course not,” Mal said. She hopped onto the back of a convenient bench and went up the railings with the casual ease of a squirrel, crouching atop the forked cast iron to reach down for Lee.