I’ve decided that the best way to tag a wall and get away with it is to look calm, cool and totally relaxed, like you have every right in the world to have a spray can in your hand and a piece of brand-new graffiti art in front of you. Often, people will give you a puzzled look, like you can’t really be serious, but mostly they will carry on walking. In London, people don’t go looking for trouble.

Even so, I don’t often have the bottle to make a hit in broad daylight. It’s five, and the street is busy, but Dave kind of got to me a little bit and I want to have the last word. The last picture, even.

I sit down on the steps of the Clapham Youth Outreach Centre, rooting around in my bag for some paint. I mean, you have to be prepared, don’t you? In case of emergencies.

I watch the people go by for a minute or two, shoppers and workers and schoolkids, and then I turn to face the dull brown doorway behind me, shake the can and start to spray.

It’s an old red can and it leaks a little on to my fingers, but that’s OK. I’m not trying to hide anything. It doesn’t take more than a minute. A fuzzy little heart shape, two dots for eyes and round, cartoon ears. A nose and whiskers. A mouse — my mark.

Nobody stops me, nobody shouts at me, nobody reports me to the police. I put the lid on my spray can, stand up and stroll along to the chippy on Clapham High Street, smiling.

There is nothing quite as good as hot chips drenched in salt and vinegar and tomato ketchup, especially eaten straight from the paper with paint-stained fingers. I’m halfway along the street and halfway through my chips when a small, scruffy, skinny dog appears at my heels. He trots alongside, looking up at me with liquid brown eyes. He’s a grubby white colour with a black patch over one eye, like a small pirate, with a filthy red neckerchief tied round his neck in place of a collar. He’s after my chips.

“Hey, pal,” I say, offering the dog one perfect, golden chip. He leaps up and takes it from my fingers, fast and graceful, and I can swear I can see him grinning.

I like dogs. I used to have one, once — well, she wasn’t mine, exactly, but still. Long time ago now. This dog is smaller, smoother and much, much dirtier. He looks like he hasn’t eaten in a week, so I feed him chip after chip as we walk along the pavement together. Then all the chips are finished, and the dog’s grin slips. He looks desolate.

“No more,” I explain, scrunching the greasy paper into a ball and chucking it at the nearest bin. I miss. The scrunched-up chip paper lands in the gutter, and a gust of wind steers it out into the road. Like a flash, the dog is after it, ducking between a couple of slow-moving cars.

“No!” I shout. “Come back! Here, boy!”

Time slows down, the way it sometimes does in dreams or on TV. The dog is in the middle of the road. A motorcyclist brakes and swerves to avoid him. My heart thumps, and I stick my fingers in my mouth and whistle, the way my dad taught me once, a long, ear-splitting call, surprisingly loud.

A girl passing by on a bicycle turns to look at me, her hair flying out behind her in golden-brown corkscrew curls. She’s the cool girl, the cute girl, from Dave’s office. Her startled eyes are green and slanted, like a cat.

The next second she lands in a heap on the pavement in front of me, the bike beneath her. Spreadeagled on the flagstones, under the spinning bicycle wheel, is the small white dog with the pirate patch.

“Omigod, omigod, I didn’t see it!” the girl is wailing. “It just ran right out in front of me...”

She drags the bike to one side, and I drop to my knees beside the little pirate dog. He takes a shallow, gasping breath like he’s just hanging on by a thread, then his eyes flutter closed and he lies absolutely still.

I think I’ve killed him.

Extracted from the novel Lucky Star by
Cathy Cassidy. Publisher: Puffin. Price: £ 8.99