At Whitehaven Sheds, the engines were ready to start work when the Tall Controller arrived. "And Marcus and Kenneth," he said at last, "I need the two of you to collect the cows from Coniston Fields and take them to Farmer Briar's."

"I thought that was Laurence's job," puzzled Tracy.

"It was, but he's needed elsewhere and there are too many cows for one small engine to deliver alone."

"We won't let you down, Sir," whistled Marcus.

"That's right," added Kenneth. "Two boiler's bubbling are better than one."

The two engines collected their cattle trucks from the Yard. At Coniston Fields, the farmhands got busy loading the cows. "You two must be very careful and pay attention," one said. "Animals are not like goods. You have to handle them carefully, like passengers."

"We will," promised Marcus.

When the cows were loaded, the farmhands left. The engines arranged the trucks into one long line. Kenneth was coupled to the train while Marcus buffered up in front. The two engines were enjoying themselves, but they remembered to be careful and puffed as gently as they could.

Then, as they rounded a bend, the signal suddenly went red. "Woah!" exclaimed Marcus, "stop!"

Luckily, they stopped just as Noel sped through with a goods train. "Sorry!" he called, "can't stop!"

"What a jolt," Kenneth wheezed. "Are the cows alright?"

Everyone looked. "The seem to be," said Marcus and they carried on…but no one noticed that the bump had caused the doors on the trucks to come loose.

Soon, Marcus and Kenneth arrived at Farmer Briar's. "Here are you're cows, Sir," whistled Marcus, "all safe and sound."

"Well done, you two." Then, Farmer Briar noticed something. "Wait a minute, some of the doors are open." He and the farmhands went to look. "The doors are loose…and some of the trucks are empty!"

"Oh no!" cried Kenneth, "they must've come loose when we stopped suddenly."

"We're sorry, Farmer Briar," said Marcus. "The signal turned red just as we were approaching it."

"They must have escaped when we weren't looking," added the Guard.

"Don't worry," said Farmer Briar, "it was only an accident, but now, we must find the rest of the cows."

"Right," agreed Marcus, "Kenneth, you stay here and help. I'll go back and look for the cows." And he raced away as fast as his pistons would pump.

"Marcus, wait!" called Farmer Briar, but Marcus didn't hear.

"What's wrong?" asked Kenneth.

"There's something important I had to tell him."

Marcus hurried back along their route. "Must find the cows, must find the cows," he puffed. He looked to his left and then, to his right until… "There's one!" he whistled, "near that old windmill. Now, for the rest."

As Marcus puffed on, he found another cow outside the town of Ravenglass and a third at Foxfield Junction, but he couldn't see any others. Then…

"Fizzling fireboxes," sighed Marcus. "I'm back where we started, but…where were the other cows?"

Marcus went back towards Farmer Briar's. He passed Foxfield Junction and Ravenglass. Then, he came to the old windmill.

"Wait…" Marcus said thoughtfully…then, he gasped. "Where's the other cow?!" Marcus raced on until he saw Farmer Briar's once more. "What happened to that cow and where can the others be?"

Marcus turned back and raced towards Coniston Fields once more. He looked left, right, up and down. He even looked carefully at the tracks in from of him, but this time…there were no cows in sight.

"Rattling rail joints!" groaned Marcus. "Where are they now?!" Marcus thought hard. "Maybe the cows are wandering back to their field, and I was going too fast to see them. If I wait here, I might see them come my way."

Marcus waited…and waited…but he couldn't see the missing cows anywhere. He was getting worried, and it was getting late.

"They must have wandered further from the tracks," Marcus wheeshed. "I'll have to look away from our main route."

The hours passed. Marcus felt like he had been puffing around in circles. He searched high and low, two and fro, but he couldn't see any cows.

Finally, Marcus steamed back to Farmer Briar's. "I'm sorry, Sir," he panted. "I did find some of the cows, but when I passed the places where I saw them again, they were gone."

"Maybe that's because some of them were here," smiled Kenneth.

Marcus was surprised; he could see more cows than there were before. "Did they walk all the way here on their own?"

"No, Marcus," said Farmer Briar, "we brought them here. I tried to tell you there was more we could do. When the other cows were unloaded, some of my farmhands stayed behind to watch them while the others went with Kenneth and I to find the cows you lost."

"We took some hay to lure them to us," explained Kenneth, "and I brought two trucks to carry them."

Marcus sighed. "I suppose I wasn't paying attention after all. Are all the cows here now?"

"All but one," replied Farmer Briar, "but with your help, it will be easier to find."

Marcus collected one of the cattle trucks and the farmhands loaded another flatbed with hay. Then, everyone split up and went looking in two different directions.

Marcus puffed along slowly, looking and listening very carefully. Then…he heard a low moo-ing sound. "I can hear the last cow!" he called.

"And I can see it," shouted Farmer Briar.

Marcus quickly collected the cow. He found Kenneth on their way, and they traveled back to the Farm together. The cow and the hay were quickly unloaded just as the sun began to set.

"Well done, Marcus and Kenneth," said Farmer Briar. "We wouldn't have found these cows without your help. Thank you."

But Marcus was still sad. "We would've found them sooner if I had taken care and listened."

"Well, I hear that neither of you have carried animals before. No one gets things right the first time and you did learn from your mistake."

"Yes, indeed," said Kenneth, "and now we know what to do next time."

And despite feeling silly, even Marcus had to smile.