“Honestly, sweetie, I am a witch, remember? Sorry it took me so long to get away, but Penny took a lot of talking to. I think I finally managed to beat some sense into her pretty little head. There’s no one more stubborn than a secret romantic. Especially one who’s taken it on herself to redeem the unredeemable.”

“Has she agreed to stop seeing Mr. Stab?” I said.

“Well, not as such,” said Molly. “The best I could get out of her was an agreement never to meet with him alone.”

I nodded reluctantly. “Penny always was stubborn. Runs in the family. Baffles me what she sees in him anyway.”

“I suppose it’s like those sad, desperate women who want to marry serial killers in prison,” said Molly. “Women always believe they can change a man, bring out the good in him through the power of their love. Some just like more of a challenge, I suppose. And Mr. Stab does have that dark, dangerous, vulnerable thing going for him. I know, I know, don’t look at me like that; I do know he’s been slaughtering and butchering women for over a century . . . but there is more to him than that, Eddie. I have seen him do . . . good things. So have you.”

“He’s Mr. Stab,” I said. “He kills women. That’s what he does. If he hurts Penny . . .”

“He won’t,” said Molly. “He’s never hurt a friend of mine.”

“If he kills her, I’ll kill him. Friend of yours or not.”

“If it comes to that, I’ll help you,” said Molly. “So, why are we here, Eddie?”

I gestured at the long steel-and-glass hangar, standing tall and proud at the rear of the Hall, though set a discreet distance away. It was a wide, steel-girdered construction, with an arching glass roof, big enough to hold several football matches in simultaneously. The family never does things by halves, even when it comes to museums hardly anyone visits anymore. I took Molly’s arm in mine and led her towards the open entrance.

“I’ve located a very useful ally in the future,” I said. “Unfortunately, he’s so far ahead of us that we’re going to have to go and get him in person. And for that, we need the Time Train.”

“Just the two of us?” said Molly.

“Well,” I said, “I did ask for volunteers, but the response was disappointing. Apparently everyone else had more sense. Time travel is always dangerous, and no one’s actually used the Time Train in ages. Probably with good reason. It’s not the most . . . reliable device the family ever built. If you’d prefer to stay behind, I’d quite understand. I’d stay behind if I could find anyone daft enough to go in my place.”

Molly hugged my arm firmly to her side. “Do you really think I’d let you go anywhere without me?”