Pip couldn’t let herself be complicit in such a greeting, so she ignored it and started down the corridor. Cara and Lauren walked beside her, Lauren having to step over Paul-from-politics who was slumped against the wall, lightly snoring.

‘This looks . . . like some people’s idea of fun,’ Pip muttered as they entered the open-plan living room and the chaos of teenage bustle hosted there: bodies grinding and thrashing to the music, towers of precariously balanced beer bottles, drunken meaning-of-life monologues yelled across the room, wet carpet patches, unsubtle groin scratches and couples pushed up against the condensation-dripping walls.

‘You’re the one who was so desperate to come,’ Lauren said, waving to some girls she took after-school drama class with.

Pip swallowed. ‘Yeah. And present Pip is always pleased with past Pip’s decisions.’

Ant, Connor and Zach spotted them then and made their way over, manoeuvring through the staggering crowd.

‘All right?’ Connor said, giving Pip and the others clumsy hugs. ‘You’re late.’

‘I know,’ Lauren said. ‘We had to re-dress Pip.’

Pip didn’t see how dungarees could be embarrassing by association, yet the jerky robot dance moves of Lauren’s drama friends were totally acceptable.

‘Are there cups?’ Cara said, holding up a bottle of vodka and lemonade.

‘Yeah, I’ll show you,’ Ant said, taking Cara off towards the kitchen.

When Cara returned with a drink for her, Pip took frequent imaginary sips as she nodded and laughed along with the conversation. When the opportunity presented itself, she sidled over to the kitchen sink, poured out the cup and filled it with water.

Later, when Zach offered to refill her cup for her, she had to pull the stunt again and got cornered talking to Joe King, who sat behind her in English. His only form of humour was to say a ridiculous statement, wait for his victim to pull a confused face and then say: ‘I’m only Joe -King.’

After the joke’s third resurgence, Pip excused herself and went to hide in a corner, thankfully alone. She stood there in the shadows, undisturbed, and scrutinized the room. She watched the dancers and the over-enthusiastic kissers, searching for any signs of shifty hand trades, pills or gurning jaws. Any over-wide pupils. Anything that might give her a possible lead to Andie’s drug dealer.

Ten whole minutes passed and Pip didn’t notice anything dubious, other than a boy called Stephen smashing a TV remote and hiding the evidence in a flower vase. Her eyes followed him as he wandered through to a large utility room and towards the back door, reaching for a pack of cigarettes from his back pocket.

Of course.

Outside with the smokers should have been the first place on her list to scout out. Pip made her way through the mayhem, protecting herself from the worst of the lurchers and staggerers with her elbows.

There were a handful of people outside. A couple of dark shadows rolling around on the trampoline at the bottom of the garden. A tearful Stella Chapman standing by the garden waste bin wailing down the phone at someone. Another two girls from her year on a children’s swing having what looked like a very serious conversation, punctuated by hands-slapped-to-mouths gasps. And Stephen Thompson-or-Timpson who she used to sit behind in maths. He was perched on a garden wall, a cigarette prone in his mouth as he searched double-handed in his various pockets.

Pip wandered over. ‘Hi,’ she said, plonking herself down on the wall next to him.

‘Hi, Pippa,’ Stephen said, taking the cigarette from his mouth so he could talk. ‘What’s up?’

‘Oh nothing much,’ Pip said. ‘Just came out here, looking for Mary Jane.’

‘Dunno who she is, sorry,’ he said, finally pulling out a neon green lighter.

‘Not a who.’ Pip turned to give him a meaningful look. ‘You know, I’m looking to blast a roach.’

‘Excuse me?’

Pip had spent an hour online that morning researching Urban Dictionary for its current street names.

She tried again, lowering her voice to a whisper. ‘You know, looking for some herb, the doob, a bit of hippie lettuce, giggle smoke, some skunk, wacky tobaccy. You know what I mean. Ganja.’

Stephen burst into laughter. ‘Oh my god,’ he cackled, ‘you are so smashed.’

‘Certainly am.’ She tried to feign a drunken giggle, but it came off as rather villainous. ‘So do you have any? Some shwag grass?’

When he stopped hooting to himself, he turned to look her up and down for a drawn-out moment. His eyes very obviously stalling over her chest and pasty legs. Pip squirmed inside; a gloopy cyclone of disgust and embarrassment. She mentally threw a reproach into Stephen’s face, but her mouth had to remain shut. She was undercover.

‘Yeah,’ Stephen said, biting his bottom lip. ‘I can roll us a joint.’ He searched his pockets again and pulled out a small baggy of weed and a packet of rolling papers.

‘Yes please,’ Pip nodded, feeling anxious and excited and a little sick. ‘You get rolling there; roll it like a . . . um, croupier with a dice.’

He laughed at her again and licked one edge of the paper, trying to hold eye contact with her while his stubby pink tongue was out. Pip looked away. It crossed her mind that maybe she had gone too far this time for a homework project. Maybe. But this wasn’t just a project any more. This was for Sal, for Ravi. For the truth. She could do this for them.