The Frying Squad sits beside the alleyway between the Paradise and Ireland estates. It is a small shop with a black and white chessboard floor and a neon-pink flying fish flashing in the window. For the past four years I haven’t been allowed to go inside. Mum wouldn’t even mention the name in our presence. Grace said we would catch carbohydrate scurvy if we couldn’t eat chips from the chip shop but Mum didn’t care and said we’d have to fur up our arteries another way. Grace told me this whole mess was thanks to Dad coming home stinking of battered sausages.

I don’t remember that. The bit about battered sausages, I mean. When I think of Dad I imagine spiced apples. And I’d almost forgotten that whenever I thought there were burglars in my wardrobe, Dad would whip my plastic sword from the toy box, fling open the door and whack the inside of the wardrobe until no thief could survive. And when I thought a monster might have hidden under my bed, Dad sneaked under there to check.

I don’t believe in monsters any more, but then again, I’m not sure I can believe in Dad either.

Charles Scallybones scuffs my leg with his claws and then puts his nose to the chessboard, searching for food.

“Your dog is vacuuming my floor,” says the man behind the counter.

“All part of the service,” I say, resting my elbows beside this huge glass jar full of prehistoric eggs. “He’ll eat anything.” I pause and take a deep breath. “I wondered if I could get…”

“Pollock?” he asks, scratching his chin.

“No,” I reply.

“Pea fritter?” His greasy quiff wobbles.

“No.”

“Cod?”

“An address for Babs,” I say. I don’t mention the busty bit, just in case.

“Do you want chips with that?”

Seems I’m being blackmailed. All I’ve got in my pocket is a button the dog ate from my blazer and then threw up in Grace’s beanie, a half-eaten chewy sweet and a fifty-pence coin. (Saint Gabriel didn’t help with number one on my list. I’ve already scored it off because I’m still broke.) Fifty pence is not enough for chips, but it is enough for a prehistoric egg from the jar saying CHEAP AS CHIPS* (*it’s your lucky day – they’re cheaper than chips).

“Pickled egg, please.” I slide my coin across the counter. As he reaches for it, I pull it back and say, “Plus Babs’s address. She used to work with you, I believe.” (Saying “I believe” makes you sound grown up.)

Charles Scallybones has moved on to eating a corner of paper napkin on c7.

The man puts the egg specimen into a paper bag. “You’ll need to eat this fast or the bottom will fall out of the bag.”

“And the address?” I let him take the coin.

“It was years ago now but I think it was the end house on Swallow Street. It’s near that big hill where all the children go. That’s all I know and it’s worth more than fifty pence.”

I push the button across the counter with my index finger. “Don’t spend it all at once,” I say. I think about winking, only I change my mind halfway through and end up walking away with a drooping eyelid.

“Your pickled egg, I believe,” the man shouts after me. “You’ve forgotten it.” I have to turn back and pick it up from the counter.

Outside, I offer the egg to Charles Scallybones, who sniffs it and jumps away as if it’s alive. A few seconds later he returns and wags his tail. Another whiff and he thinks it might just be edible. The pickled egg is swallowed whole. A moment later, the pickled egg comes back scrambled.

The hill, I tell myself as I walk back home, is not more than twenty minutes from our house. I’ve skateboarded down it many times. Is that where Dad has lived since he walked out? But it’s so close that we could have easily bumped into each other. And if it’s so close, why didn’t he come and visit? I go through a whole list of possible reasons why not, but none of them amount to much. The fact remains that Dad didn’t come. But it doesn’t stop me going to him.

Part two of Operation Baskerville involves the searchyourstreets website. With Dad’s address in my mind, I switch on the computer and check out Swallow Street. (A good detective does stuff like this. You don’t think Sherlock Holmes would storm straight in, do you? Instead, he would prepare, plan it out and make deductions before visiting the scene.) I find the end house.

For a start, this is no Buckingham Palace x 1, let alone x 3. No fancy walls and curling iron gates. As for a flag fluttering in the wind, forget it. What this turns out to be is a normal-looking house with a neat hedge and wooden fence. To the side there’s a long alleyway littered with bins. I zoom into Dad’s back garden, where there are rose bushes, trees, a pathway that looks like large pebbles dotted on the lawn, a bird fountain and a wooden shed. All very ordinary for a celebrity, that’s for sure.

To the right of the house, further down the road, there is a wooded area and to its side drops Skateboarding Hill, which leads down to Paradise estate. I’ve been in that wood a few times. Once I built a den out of cardboard in there, only it rained and I ended up walking home looking like a papier-mâché monster.

The first thing I think, as I jam my skateboard under my arm and make my way to the summit of Skateboarding Hill, is how much I want this. I didn’t think it was possible to need my dad as much as I do now. Down below in the valley, November has just tipped into December and frost is spreading like a glittery disease through the streets. In the distance I can see the fairy lights around Aladdin’s Supermarket, where Mum is at this very moment probably ding-dinging frozen Brussels sprouts through her scanner. Far beyond Aladdin’s, just on the edge of the Paradise estate, the dark frosted fields roll away into eternity. You can’t see what is beyond and although I know it’s just the next town, I imagine it to be the end of the world.

Above me the inky sky has been flicked with a white paintbrush. There are zillions of tiny snow-white dots, some big, some small, some splattered. And the crescent moon is like the tip of Ninja Grace’s manicured nail. I breathe in and out. Plumes rise into the chilled air. I’m going to do this. I’m going to do it right now.

I hide my skateboard in the wood, thinking I’ll pick it up on the way back home. No point in carrying it over to Dad’s house. At this stage I haven’t planned what I’m going to do when I get there. But that’s okay. I’m going to take everything as it comes. If I decide to ring the doorbell and wait for Dad I will. If I want to ring the doorbell and hide then I can do that too. In fact, I can do anything I want, because I’m the master of Operation Baskerville.

I am invincible.

I am a genius.

I am unstoppable.

I am scared.

Dad’s house sits on the junction between one row of houses and the beginning of another. Just a glance at it and my stomach lurches. At first I walk past, whistling. Whistling is never suspicious, oh no. Next door, the neighbour’s curtains move and I’ve been spotted, so I run into the alleyway at the side of Dad’s house. As I rest my head against the cool shadows I hear a cat meow and footsteps coming towards me. A bin bag rustles. I haven’t got time to wonder what Sherlock Holmes would do. Instead, this is what Dan Hope does: I climb up onto a bin and throw myself over the nearest fence and into a garden. Behind me I hear a bin lid lift and the thump of rubbish. The footsteps dissolve.

There is good news and bad news. The good news: I have avoided being discovered lurking in the alleyway outside Dad’s house. The bad news: I am now lurking in Dad’s garden. Eventually I sneak down the garden path. And here’s the odd thing: when I was on searchyourstreets I didn’t see the trampoline by the fence. Nor did I spot the small football net or the discarded plastic water pistol. They look out of place in the garden, as if they don’t belong.

At the point where I reach the trampoline, the kitchen light goes on and I can hear a key rattling in the back door lock.

“Hello?” A voice cuts through the darkness.

Sweat spouts from my scalp and a small river snakes through my hair as I run down the garden and throw my body against the shadowy side of the shed.

“If someone is hiding in the garden I’ll ring the police. I’ve got speed dial on my mobile.”

I hug the dark, trying not to breathe.

It’s hard not to breathe. Breathing’s sort of important.

I know I can’t hide here for ever and I pray for the person to go back into the house. And I think they might have done if I hadn’t just then seen a huge hairy monster rise from the depths of the garden path and throw itself against my leg. I kick out and my trainer connects with a furball. It lets out an almighty hiss that breaks the silence. To tell you the truth, that’s the moment when it all goes wrong and I forget I’m supposed to be breathing like a sleeping baby and start chuffing like an old steam train climbing Mount Everest.

The cat, because that’s all it is, patters away from me as the dark figure runs towards me, screaming and hollering how they knew there was an intruder in the garden. “If you’re paparazzi there’s going to be trouble. There are laws against this sort of stuff. You can’t spy on a minor just because my dad is famous.”

My dad?

Your dad?

Our dad?