The train crawled towards Highfield at the pace of a dying slug. It was almost dark, and so far beyond the back of beyond that there was only one other person left in my carriage. He sat hunched over a bag of crisps, snatching them from the packet one by one and crunching them with quite unnecessary violence. I considered moving carriages, but then he might have thought I was scared of him. (Which I was, but I didn’t want him to know that.)

At this rate Mum would probably be in Venice before I got to Highfield Station. And then it was still another five miles by car to the house. With a godmother I knew nothing about, except she was seventy-two years old.

“You’ll like her,” said Mum. “She’s lovely.”

Which meant nothing. It’s what Mum says about everybody who isn’t an actual criminal. Anyway, all her attention at the time was on the half-packed suitcase open on her bed.

“This one or this one?” she asked, holding up two floaty summer dresses. I shrugged. It was freezing in London. But in Venice, of course, it would be perfect summer weather.

“Maybe both,” said Mum. “They weigh practically nothing anyway.”

It wasn’t meant to be like this. I was supposed to be staying with my best friend Nisha while Mum was away. But then Nisha’s grandfather died and they had to go to India, so Mum decided to pack me off to my godmother’s instead. I’d much rather have stayed in the flat by myself, but she wouldn’t hear of it.

“You’re only thirteen. I can’t leave you on your own for five days. Anything could happen.”

“What could happen, exactly? I’ve lived here my whole life and nothing’s ever happened yet. Anyway, I can have friends round.”

“That’s exactly what I’m worried about,” said Mum. And then, as I opened my mouth to argue, “Don’t even bother, Evie. I’m not letting you stay on your own for a week and that’s final.”

So. Here I was. Happy holidays, Evie.

Big fat raindrops started to splat against the windows. There was nothing outside the train but fields and trees, all bleak and bare in the fading light. We hadn’t passed a house for miles.

On the plastic table, the cracked screen of my phone lit up with a text. I grabbed it with pathetic eagerness, hoping it was from a friend. But it was my so-called godmother.

Well, what a lovely welcome.

I texted Mum to inform her of this new development. Maybe she’d actually feel a twinge of guilt about abandoning her only daughter to a woman who clearly cared more about some stupid village meeting than she did about looking after me.

If Mum could drag her eyes away from her perfect new husband for long enough to check her phone, that was. Which was doubtful.

I pressed Send, but there was no signal. Unbelievable. We weren’t even in a tunnel. Was this what it was like in the countryside?

I suddenly had a terrible thought. What if there was no signal at Charlbury? If I had to spend five days cooped up in a random old lady’s flat with no way of communicating with the outside world, I would literally die.

The rain was lashing down now, making long diagonal streaks on the windows. I thought about getting my sketchbook out to draw it, but then the train started to slow down.

Highfield. This was it.

Nobody else got out. The station was deserted. But there was one cab parked on the kerb. I walked towards it and the driver opened his window. I gave him the address, trying to sound as though I gave instructions to taxi drivers all the time. He nodded but didn’t say a word, which was really creepy. I couldn’t believe my godmother was actually ordering me to get into a car with a complete stranger. But I couldn’t see a bus stop anywhere and there was still no signal on my phone. So I didn’t really have a choice.

Within about a minute we left the houses behind and there was nothing beyond the rain-streaked windows but darkness.

The driver stayed silent. All I could see was his thick neck and the back of his bald head.

What if he wasn’t taking me to Charlbury at all, but to some deserted place where he was planning to kill me and bury my body?

After what felt like hours, he turned on to a narrow winding lane. There were no other cars on the road. I felt sick with fear. I kept my fingers curled around the door handle in case I needed to make a quick getaway. He didn’t look very fit. Maybe I could outrun him. Otherwise I’d have no chance.

The car slowed down. I thought I was actually going to throw up. I said frantic prayers inside my head. I’m not religious, but there was no one else to turn to.

He turned off the lane on to a narrow, tree-lined driveway. In the light of the headlamps, I saw a huge old house at the end of the drive.

“Charlbury House,” he said, slowing to a halt in front of it.

I felt weak with relief. I paid the fare – half my emergency money gone already – and got out of the cab. The wind was so strong that I could hardly open the door. I still felt shaky with fear, even though there was nothing to be scared of any more.

The rain was pelting down. A gust of wind whipped my hair across my face. As the taxi drove away, I pushed the long dark strands out of my eyes and looked up at the house.

It was massive. A huge, ancient, spooky stone mansion. Enormous windows with carved stone frames, and a grand flight of steps leading to the biggest front door I’d ever seen.

How could Mum have forgotten to mention I’d be staying in a mansion?

I walked up the steps, bumping my case behind me. A light came on above the front door, illuminating slanting rods of rain. Raindrops bounced off the stone slabs. There was a big puddle right in front of the door, where the stone had worn down.

Screwed to the wall beside the door, looking completely wrong on the ancient stones, was an ugly modern row of bells and an intercom. I pressed the bell for Flat 9.

I waited for ages but there was no answer. I pressed the bell again, harder this time.

Nothing. Either the bell wasn’t working, or she was still not home from her meeting.

Honestly. You’d think she might have made a tiny bit of effort, instead of leaving her goddaughter standing in the rain while she sat in a nice warm room wittering on about the village scone-baking crisis or whatever it was that was so much more important than collecting me from the station.

Unless I’d pressed the wrong bell. I pulled my phone from my pocket to check the address.

But my hands were cold and wet, and the phone slipped through my fingers. I tried to grab it, but my fingers closed around thin air and my phone splatted right into the middle of the puddle.

“Oh, no, no, no!”

I fished it out of the water and wiped it frantically on my coat, but my coat was soaking too, and the phone was just getting wetter. I unzipped my coat and tried to rub it dry on my top.

A beam of light shone on the front door and I turned to see a sports car speeding up the drive. It veered sharply in front of the steps, throwing up gravel all around it, and braked next to the house.

Somebody got out of the car and crunched briskly across the gravel. The person bounded up the steps, and I saw it was a little old lady. But not a normal old lady. She wore orange baseball boots with black trousers and a red jacket, and a broad streak of her silver hair was dyed bright pink.

“Are you Evie?” Her voice was clipped and businesslike. “You look very like your mother. I hope you haven’t been waiting long. I thought I’d be home earlier, but these councillors do love the sound of their own voices. Never use one sentence when you can use ten, that seems to be their motto.”

I said nothing. I was staring at her hair.

“Do you like it?” she asked, pulling out the pink strand with her thumb and forefinger. “I was tempted to dye the whole lot, but it takes a lot of work to maintain it, apparently. I might still do it at some point though. It’s very cheering when one looks in the mirror, I find. Distracts from the wrinkles. Now, where’s my key?”

As she rummaged in her shoulder bag, I looked at her jewellery. Enormous earrings, a huge necklace and a vast number of heavy-looking rings on her slim fingers. Her nails were painted silver.

From the depths of her bag, she pulled out a key ring in the shape of a skull.

“Are you Anna?” I asked, trying to adjust the image I had formed in my head to this pink-streaked, orange-booted, silver-nailed reality.

“I am. I suppose I should have said. What’s wrong with your hand? Have you hurt it?”

“It’s not my hand,” I said, withdrawing it from inside my coat. “My phone fell in that puddle. I was trying to dry it.”

She frowned at the screen. “The water will have got in through the cracks. It’s probably...