Buster wagged his tail. He meant to look after Bets, not have Bets look after himl He too felt sad when he saw the children going off without him. But he knew that he could never run fast enough to keep up with bicycles.
It had been raining in the night and everywhere was muddy. Bets thought she had better put on her rubber boots. She went to get them. Buster pattered after her on muddy paws.
"It's a pity you can't wear goloshes or something, Buster," she said. "You get awfully muddy."
The two of them set off for a walk. Bets went down the lane to the river. She chose a little path that ran alongside the river for some way, and then turned back again across a field that led to the stile where the children had seen the exciting footprints a few days before.
Bets danced along, throwing sticks for Buster, and remembering not to throw stones for him to fetch because Fatty said they broke his teeth. She stooped down to pick up a stick - and then stood still in the greatest astonishment.
There, plainly to be seen on the muddy path in front of her, was a line of footprints exactly like the ones the children had found by the stile! Bets by now knew the prints by heart, for she had gazed at Fatty's drawings so often. She felt absolutely certain that they were the same. There was the rubber sole with its criss-cross markings, and the little squares with the blobs at each corner!
"Ooh, look, Buster," said Bets at last. She could feel her heart thumping with excitement. Buster came to look. He sniffed at the footprints and then looked up at Bets, wagging his tail.
"They're the same prints, aren't they, Buster, dear?" said Bets. "And listen, Buster - it only rained last night -so some one must have walked along here since then - and that some one is the person we're after - though we don't know who! Oh, Buster - what's the best thing to do? I do feel so excited, don't you?"
Buster capered round the little girl as if he understood eveiy single word she said. She stood for a moment or two looking down at the line of footprints.
"We'll follow them, Buster," she said. "That's what we'll do! We'll follow them. See? I don't know how long it is since the person walked along here, but it's not very long, anyway. Come on - we may even catch up with the person who made the prints. Oh, this is exciting!"