Every night at exactly nine o'clock, the scratching began. It started above Jack's bed, scuttled across the ceiling and stopped right over the wardrobe. Then — thump! Something heavy dropped onto the roof outside.

'It's a monster,' Jack whispered to his sister, Mia.

'It's a possum,' said Mia, who was ten and knew everything. 'Brushtails live in roofs all the time. Nan had one for years.'

Jack wasn't so sure. The next night he waited with his torch under the blanket. Scratch, scratch, scuttle. Thump. He crept to the window and shone the torch into the dark.

Two bright eyes stared back at him from a branch of the lemon tree. Big ears. A pink nose. A bushy black tail wrapped around the branch. The possum blinked, then calmly picked a lemon leaf and began to chew.

Jack laughed so loudly that Mia came running in.

'See?' she said. 'Not a monster.'

'No,' said Jack. 'But it's eating our lemon tree.'

The next day, Dad put a wooden possum box high in the gum tree at the back of the yard. He blocked the hole under the roof tiles with wire. Within a week, the scratching above Jack's bed had stopped. Now, every night at nine, Jack looks out the window and waves to the possum climbing out of its new home.