“She’s not trying to escape. She’s setting the whole house on fire,” Rose exclaimed “There are so many little servants’ corridors she can get through.”

“Call the fire brigade and get the servants out to safety,” I said. “There’s nothing we can do from here.”

“I must find my mother,” Rose said, suddenly realizing. “Oh God. I hope she’s all right.” She darted away from me shouting, “Mummy, where are you? There’s a fire.”

I heard an answering voice and heaved a small sigh of relief as her mother emerged from her bedroom.

I ran back and found the inspector coming down from the floor above. “Nobody up there,” he began, then smelled the smoke. “What the devil?”

“She’s setting rooms on fire,” I said “She locked up Mrs. Summers. We’re going to call the fire brigade.”

“Georgie, are you all right?” Belinda was coming up the stairs toward me.

“I’m fine. Look after Rose and her mother. I have to call the fire brigade.”

Servants had begun to appear from various parts of the house. “There’s a fire in the library,” a maid was wailing. “All the books are burning. It’s going up like a torch.”

“Make sure everyone is safe and accounted for,” Rose said.

The fire brigade promised to get to us as quickly as possible, but they were a good ten minutes away. The footman started trying to organize a bucket brigade but the store cupboards by the kitchen were on fire and we couldn’t get at the water. Someone ran for an outside hose. But there were too many fires, in too many places. It seemed that wherever we went she was one step ahead of us, knocking over lamps, setting the oil on fire and then disappearing to the next location. We could hear crackling and roaring as the fire took hold. Eventually we all had to retreat outside and wait for the fire brigade to arrive. The servants were huddled together weeping. The outside staff had joined the footman and were trying to be useful but with little success. Two fire engines finally came, one of them a tanker of water, and firemen started to spray their hoses, but it was clearly too little, too late.

“I’d just like to know where the damned woman is,” DI Watt growled. “I’ve got someone guarding the back of the house. She hasn’t emerged yet. She’ll be burned to a crisp if she doesn’t come out soon.”

“That’s probably what she wants,” Rose said. “To go down in a blaze of glory.”

“Save us the expense of a trial, I suppose,” the inspector muttered.

“Where was her room, Rose?” I asked.

“I don’t really know. I didn’t pry much into where the servants slept. She always took care of that side of things. She was so darned efficient.”