At school on Monday morning, Billie, Jack and Alex are still laughing about the strawberry-stealing possums as they wait for Mika. She arrives just as the bell goes and the four of them walk to class together.

‘So, did Gus fix the hole in the fence?’ Alex asks Mika.

Mika grins. ‘He sure did! Mum called him over after you went home and he hammered a piece of wood over it. I can’t believe we didn’t see it there when we were looking for clues that first day.’

‘I guess we didn’t think of looking at the fence,’ Jack says. ‘The netting was attached to it so well, who could have known there was another way in?’

‘So, are you happy we caught the thieves?’ Billie jokes, poking Mika in the ribs.

Mika shrugs. ‘Yeah, I guess. But Mum and I feel kind of sorry for the possums, too. We left some apple cores by the strawberry patch. They’re probably not as yummy as strawberries, but at least the possums can still feed their babies.’

‘Another mystery solved!’ Alex says, as they walk into class. ‘I wonder what will be next?’

‘I hope we don’t have to wait too long,’ Billie says happily. ‘We’re getting pretty good at this. I’m ready to solve another one already!’

They pull up their chairs and sit down at their desks, chatting together while they wait for Mr Benetto to arrive. It’s unusual for him to be late. Usually he is already sitting at his desk when the class wanders in.

Finally, he strides into the room, his face as dark as a storm cloud.

Billie has never seen him look like this before. The rest of the class notices too, and one by one they fall quiet.

When Mr Benetto opens his mouth to speak, his voice comes out low and angry. ‘I have just come from a meeting with our principal and I have some very grave news to share,’ he begins. ‘Something valuable has been taken from her office and someone in this school is responsible.’

Billie feels a shiver pass through her. She glances briefly at Jack, then Mika, then Alex. She knows that none of them would dare to look back at her in case Mr Benetto catches them, but she is certain she knows what they are thinking.

The Secret Mystery Club has another mystery to solve. And this one might be the most serious yet!