Billie makes her way down the street with the rest of the Secret Mystery Club.

When they get close to the spooky house, they split into two groups. Alex and Jack slip around the side of the house.

Billie and Mika wait a minute, then they walk up to the front gate. This is the closest Billie has ever been to the spooky house. Usually when she and Jack walk past, they cross to the other side of the street.

She feels a buzzy mix of excitement and fear. Even though she knows that a witch probably doesn’t live there, her heart is still beating very fast.

Billie slowly pushes open the front gate. It lets out a long squeal.

A black cat scoots across the front porch and around the side of the house.

‘A witch’s cat!’ Billie whispers to Mika. ‘That is definitely a witch’s cat.’

Mika’s eyes become as round as moons. ‘Are you sure we should knock on the door?’ she says.

‘Of course!’ says Billie, but she feels her heart beat even faster.

The front garden is a tangled mess of weeds and bushes.

Billie and Mika tiptoe along the cracked path towards the pale green door. The tall grey house is faded and peeling. Big flakes of paint curl up to show the silvery boards beneath.

‘This is so a witch’s house!’ Billie hisses.

‘Stop it, Billie!’ Mika says. She stops walking and screws up her face. ‘Or I’m going home!’

Billie giggles. Even Mika believes my spooky stories now! she thinks.

‘There’s no such thing as ghosts and witches, Mika!’ she says. ‘Everyone knows that.’

Mika frowns. ‘That’s not what you said before.’

‘I know, but I was just fooling around,’ Billie says. ‘I wanted to have a mystery to solve! We’ll just knock on the door to see if anyone lives here, and then we can go home.’ She grabs Mika’s hand.

They step up to the door. Billie lifts a hand, pauses for a second, then gives the door three loud knocks.

The street is completely quiet except for the rustle of wind in the trees. In the distance, a car starts up.

‘There’s no-one here!’ Mika says after a moment. She looks relieved. ‘Come on, let’s find the others.’

‘Wait!’ says Billie. ‘I think I hear something.’ She puts her ear to the door.

From deep inside the house comes the strange noise she has heard before. A whirring machine noise, grinding and crushing.

‘That must be the witch’s kid-crushing machine!’ Billie says in a low voice to Mika.

Mika turns as pale as a ghost. ‘Billie!’ she says angrily. ‘You just said there’s no such thing as witches. Now you’re trying to scare me! I’m going back to your house. This isn’t fun anymore!’ She marches back down the garden path.

‘Wait!’ whispers Billie. ‘I think I can hear someone. Really!’

But Mika stomps through the gate and closes it behind her. Then she jogs around the side of the house to look for Alex and Jack.

Billie watches Mika go. She feels a bit bad for scaring her friends.

This house is pretty spooky. Maybe this wasn’t the best place to look for a mystery after all?

Billie listens to the noises from deep inside the house. Whirring, grinding, creaking noises.

Then a noise like footsteps. Slow, heavy footsteps on creaking floorboards. Coming closer. And closer.

Suddenly, the door is flung open. Billie looks up. And gasps.

Standing in front of her is the scariest woman Billie has ever seen. She has long white hair and is wearing a long black dress. Just like a real witch! When Billie looks at her long skinny fingers, she sees that they are spattered with red.

‘Hello?’ the woman says. Her voice is croaky like a frog. She curls back her lips to show a line of yellow teeth.

Billie drops her basket of lollies in fright. She runs down the path and through the rickety gate, her heart pounding in her ears. Then she runs all the way home.