The first class for the day is art, which Billie is very happy about. Firstly because she loves art and secondly because their teacher, Ms Parkes, doesn’t mind if they talk in class. It is the perfect opportunity to do some secret detective work.

‘OK, kids!’ Ms Parkes calls out as the students shuffle into the room and perch on stools around the big tables. ‘Today we are going to work on our Saving The Environment posters to put up around the neighbourhood. Who can remember some of the topics we discussed last week?’

Lola shoots up her hand. She always likes to be first to answer questions.

‘Yes, Lola?’ says Ms Parkes.

‘Recycling. Saving water. Not littering …’ Lola says, counting the topics off on her fingers.

Ms Parkes interrupts her. ‘Excellent, Lola. Anyone else?’

Billie puts up her hand. ‘Not wasting electricity?’ she says.

‘Good,’ says Ms Parkes. ‘Benny?’

Benny looks up, quickly. He has been staring out the window. ‘Sorry?’ he says, his cheeks turning pink.

‘Have you thought of a topic for your poster?’ Ms Parkes asks.

Benny looks down at his desk. ‘Um, not yet,’ he says quietly.

‘How about “Not destroying other people’s things”?’ Lola says, glaring at Benny.

Benny glances at Rebecca and his cheeks turn from pink to red.

‘That’s enough,’ Ms Parkes warns Lola. ‘Benny has already been punished for what he did.’

‘But, I didn’t …’ Benny mumbles, then he stops and looks back out the window, frowning. Billie feels sorry for him.

‘All right, everyone, I’d like you to work in pairs,’ Ms Parkes tells the class, ‘so make sure you choose someone you are going to work well with.’

Billie jumps up and walks over to Benny. He looks up at her in surprise.

Jack looks surprised, too. He and Billie always work together. But Billie gives him a secretive look, which he understands straight away. He nods and walks off to find someone else to work with.

‘Can I work with you?’ Billie asks Benny.

Benny narrows his eyes suspiciously. ‘Why?’ he says.

Billie shrugs. ‘Because you’re good at drawing trucks.

I want to do a poster on recycling, and I need someone to draw a recycling truck.’

‘Well, all right,’ Benny says slowly, looking pleased. ‘But who’s Sam going to work with?’

‘I’ll work with Sam,’ Alex says quickly. He taps his top pocket where Billie knows he has hidden his voice recorder. So Sam walks over to sit next to Alex, and Billie sits down next to Benny. She opens up her sketchbook.

‘So, I was thinking we could draw a normal rubbish truck and a recycling truck, then draw the different things that go into each of them,’ Billie says. ‘You know, like glass and paper and milk cartons go in the recycling truck, and plastic bags and other stuff go in the rubbish truck. What do you think?’

Benny shrugs. ‘OK,’ he grumbles.

‘Are you still upset about what Lola said?’ Billie asks.‘Why do you even care what she thinks?’

‘I don’t!’ Benny scowls. ‘It’s just that everybody believes her and not me.’

‘Well, you do do lots of silly things, Benny,’ Billie says. ‘Why should we believe you didn’t do it this time?’

Benny frowns. ‘I wouldn’t do something like that to…’ he stops. ‘Never mind. Nobody believes me anyway.’ He looks over to where Rebecca and Lola are sitting. When Rebecca looks up, he quickly looks away, his cheeks flaring pink again.

‘Rebecca won’t even talk to me anymore,’ he mumbles. ‘She won’t even look at me! She used to be nice to me, but now…’ He sighs.

Billie’s brain begins to whizz. Suddenly she thinks she understands. A smile creeps over her face. ‘You … like Rebecca!’ she whispers slowly to Benny.

‘What?’ Benny says, his eyes flashing. ‘Don’t be silly, of course I don’t! That’s stupid!’

‘You do!’ says Billie, grinning. ‘I can tell! You watch her all the time. And you go all funny whenever she looks at you.’

Benny looks like he might cry. ‘Billie,’ he begs. ‘Please be quiet! She already hates me. Don’t make it worse.’

Billie puts her hand on Benny’s arm. She has all the information she needs. Why would he put leaves in Rebecca’s sandwich if he likes her? she thinks. That doesn’t make any sense!

‘Don’t worry,’ she says kindly. ‘I won’t tell anyone.’

Benny breathes out in relief. ‘Promise?’

Billie nods. ‘I promise,’ she says.

Now Billie is one hundred per cent sure that Benny didn’t commit the crime. She looks around the classroom. Everyone is chatting noisily about their projects.

But then if Benny didn’t do it, who did? she wonders.