the cupboard, glaring at the wall.
Their golden ears were pricked into flags. They tilted their heads to listen. Then they scrabbled at the wall with their twelve golden paws.
They were not at all pleased when Lulu and Mellie scooped them up around their furry middles, carried them to the living room, dumped them on the sofa, and closed the door.
âNow listen!â said Lulu to Mellie.
They listened and sure enough they heard Ratty, climbing around on the other side of the wall.
âHe must have climbed right down from the roof!â whispered Mellie.
Lulu and Mellie unlocked the back door and tiptoed into the garden and were very surprised not to see Ratty clinging to the wall.
âBut we heard him!â said Lulu, very puzzled, and she stepped back into the kitchen to listen. Once again, there was Ratty, plain to be heard, climbing around.
But outside, no Ratty. Nothing.
So Mellie stayed inside and Lulu found a flashlight and went outside and they left the door open and Mellie called directions. âHeâs right beside the window! Now heâs a bit lower! Heâs halfway down now, between the window and the floor!â
Lulu peered, more and more puzzled, at the outside wall of Nanâs little kitchen. Then suddenly she understood. Walls were not one brick thick, like Lego house walls. They were two bricks thick. There was an inside wall and an outside wall, with a gap in between.
And in the gap in between was Ratty.
When Lulu understood this she rushed inside and told Mellie they must call the fire department to come and knock down the house.
âThe whole house?â asked Mellie, dreadfully shocked.
âOnly the back half,â said Lulu.
âThatâs a lot of house, though,â said Mellie, and she picked up the phone and held it behind her back to stop Lulu from arranging anything reckless.
âItâs the wrong thing to do!â said Mellie. âEspecially on Nanâs birthday! Just listen to Ratty! There he is again! Right under the window.â
They both went outside again, and shone the flashlight at the wall, and while they were there Lulu noticed something.
Not all the bricks were the same. One, low down, almost on the ground, was not solid. It was brick colored. It was made out of brick. But it looked like a little grating. A little grating, an air brick, with little square holes like windows, opening into the wall.
Lulu lay down on her stomach and shone her flashlight through the holes.
There, on the other side, was Ratty.
For a moment it seemed to Lulu and Mellie that all their problems were solved. There was Ratty. They had found him. And Nan was still asleep in bed.
âAll we have to do,â said Lulu, âis to make those little holes big enough for Ratty to squeeze out.â
âEasy peasy!â said Mellie at once.
They fetched from the kitchen the tin opener and a screwdriver and they set to work.
After a while they went back for the potato peeler and some spoons.
Small flakes of air brick broke away in thin sharp splinters.
Mellie crept upstairs and brought down their swimming goggles.
Ratty scurried around on the other side of the wall. He was very happy. He had never had any adventures living with Emma Pond.
Time passed.
The stars swung around the sky.
Lulu and Mellieâs knees began to ache.
âWhat we need,â said Lulu, âis a very big hammer.â
For as long as Lulu and Mellie could remember, Nan had lived alone in her little bright house. But once there had been a big, quiet Granddad living there too. He had liked making things and he had owned a shed full of tools. It was still there, right at the end of the garden, beyond the orange and lemon tree.
Mellie took the flashlight and visited Granddadâs shed, and she came back with a very big hammer indeed.
âPerfect!â said Lulu, and she seized it from Mellie, swung it mightily back into the air, and walloped the air brick with