"Thank you so much for having us," said Penny, shaking Miss Ballinger by the hand. "We have enjoyed it so... You must come and see us some time."

"Thank you," their hostess said grimly. "I most certainly will!"

"Keep quiet. Go steady," Jon muttered as they left "Beach View" and shuffled through the shingle again. "Don't let her see us talking and don't try and look mysterious. Just look slightly soft, like you usually do!"

But when they were out of sight and had turned on to the road they both started to talk at once.

"She gave herself away, Penny. I knew she would! She was clever about the birthday date, though, wasn't she? I know jolly well I nearly gave the game away myself at that."

"What date? What did she mean, anyway?" Penny said wonderingly.

Jon clapped both hands to his head in despair. "April the seventh, you idiot! The date on the clue. Don't you remember?"

"Oh, of course!" Penny laughed. "I'd forgotten about that stupid scrap of paper."

"Forgotten about that stupid scrap of paper!" Jon repeated, as if in a trance. "She's forgotten already. Don't you realize that everything is proved now? It shows that Slinky passed the clue to someone else, who passed it on to Miss B. There's no doubt of that now. She thought we might give ourselves away when she mentioned April the seventh. I nearly jumped, but she was watching you, luckily for me. No wonder it didn't affect you!"

"I just thought she was mad," Penny said complacently. "I always hated dates, anyway, and I never remember them... But, Jon! She does want that map, doesn't she? What do you think she would have done if she had known it was in your pocket?"

They were walking now on a rutted track leading inland from the beach. Just before it joined a more important road they moved aside to make way for a cyclist, who looked at them curiously as she pedalled down towards the bungalows. She was a very pretty girl of about twenty, wearing a white mackintosh and sandals on her bare feet. Jon turned to look at her as she passed.

"You'd know her again, wouldn't you?" Penny said coldly as they reached the road. Jon looked at her in surprise, but had the sense to say no more.

They were still talking about Miss Ballinger a quarter of an hour later and had nearly reached the corner of the road under Winchelsea hill, where they hoped to stop the bus, when the sound of a bicycle bell behind them made them jump apart.