Dot frowned. She kind of knew that sound but she couldn’t remember where she’d heard it before.

Then she did. She’d gone out Wiz and Mum and Dad on a country walk once. It was in the autumn and it was one of those blustery days when the wind blows and the clouds seem to be chasing each other across the sky. They were walking round a field when they came to a big group of tall trees – where big black birds called rooks were flying in and out of the branches, high up in the sky, calling to each other as they flew. That was the noise she’d heard – the “CRAAACK!” Or at least it was very like it…

Adrienne whirled round, her little eyes sparkling and her tail frisking from side to side behind her head. The tufty bits on top her red squirrel ears were standing straight up too! She laughed excitedly.

“Ah – ha!” she said once again. “Bon! We ‘ave called him!”

?”mih dellaC” said Wiz anxiously, still all back to front.

“Mais oui!” (which means “But yes!”) said Adrienne. “Sometimes when you put an Inverter Code in like I just did, it ‘as just enough power to reach the nasty person who ‘as done ze inversion, even when it is out of date … but because ze code ‘as changed ‘e will only know that something is going to happen to change evryzing back again. Zat is what we say is “calling” ‘im.”  She stopped and listened with her head on one side. “Zo – in a moment I zink we will be seeing Monsieur Blackshanks ze Baron, and zen...”

“Zen - what?” said Mr Mouse rudely. “The guy’ll make break for it, for sure! One look at us and he’ll be off like an Apollo moon rocket!”

“Oh no ‘e will not, mon ami” said Adrienne calmly. “And if you come back on board my search engine, I will show you why. But you must be quick        because if we can ‘ear ‘im, he is VERY close to us!”

“CRAACK!” went that sound again.

“Got it!” said Dot. “It’s like the noise a crow, or a rook makes… what’s it called?” She screwed up her eyes to concentrate. “Yes! Cawing, that’s what that noise is called!”

“Back on board everyone please!” said Adrienne sharply. “Vite, vite!” (which means quickly, quickly!) In her hand, the little machine with the tiny umbrella had started to vibrate with a kind of clicking noise, and the umbrella was spinning round again. “Ze baron has entered our search sector again!”

“!ereh em evael t’noD” said Wizzie with a worried whine (or enihw!) Dot bit her lip and turned to Adrienne. “We can’t leave Wizzie!” she said.

“We won’t!” said Adrienne shortly, jumping into her search engine pilot’s seat. “But… Wizzeee… you won’t see us for a while, OK?” Wizzie whined even more anxiously, his tail right down on the ground.

“What now?” grumbled Mr Mouse, climbing in beside Dot.

“Zis!” said Adrienne shortly. She lifted a little flap over a button  marked 'Escape To Zero' on her control panel – and hit it with a stab of her paw.

With a gentle hiss, the shiny red search engine floated upwards – stopping and hovering just a few metres above the search zone floor. But after that - nothing. Dot shook her head. What was happening NOW?

But whatever it was Wizzie clearly didn’t like it. He let a sharp, worried bark. “?uoy era erehW” he said.

“What’s the matter with Wiz?” Dot asked Adrienne. She hated to see him look so frightened. 

“Try and put your hand outside ze engine” said Adrienne quietly.

Dot tried. She couldn’t.  It was like pushing against very strong cling-film – her hand just wouldn’t go further than the outer edge of the truck she was sitting in. Whaaaaat…?

“We are in an Invisibility Capsule” said Adrienne in a whisper. “Wizzie cannot see us – nor can ze Baron. Zat is ze way we will catch ‘im. But, we must stay ver’ quiet because if – ah!” She put her paw to her lips and then pointed down to the search zone floor.

Dot looked – and gasped. What in the name of the Net was happening now?