Right at the top of the list, marked as “of the highest degree of urgency” and with the subject given in block red capitals as SOMETHING SERIOUS, there was a message by my old friend Lady Clamydia Featherlight-Plume. 

“Contact me at once,” she wrote. 

“Something serious is afoot. 

“My marriage could depend on it,” and it was signed “Clammy”, a form of her name that she only uses at moments on extreme tension.

I rang her immediately, of course, and asked what the problem was. 

“It’s Lord Plume,” she said. 

“Something he asked me last night has made me frantic.” 

“Go on,” I said encouragingly. 

“Tell me what he said.  

“You can trust me to be completely discreet.” 

“Oh dear Beachie,” she said. 

“I knew you’d help. 

“What he said concerned three suspicious husbands. 

“Does he imagine I’ve been up to something? 

“Whatever can give him that idea? 

“I’ve racked my brains and can’t think.” 

“Did he go on to say anything about a river?” I asked. 

“How do you know?” she squawked. 

“Are you in it with him? 

“Are you suspicious too? 

“If so, who’s the third? 

“Come on fellow, out with it.” 

“It’s a puzzle,” I began. 

“It certainly is,” she said. 

“There’s the two of you and someone else. 

“Are you expecting me to guess?” 

“No, no, not at all,” I reassured her. 

“It’s a medieval puzzle about three suspicious husbands and their wives who all want to get across a river but the boat will only carry two of them. 

“None of them will leave their wives with either of the other husbands, so how do they get across?” 

“Why don’t they walk across a bridge or get a bigger boat?” she asked. 

“For the purpose of the puzzle, we assume those options are ruled out,” I said. 

“Look, I’ll tell you how it’s done.” 

“Not until you’ve told me who the third jealous husband is,” she said. 

“It doesn’t matter,” I insisted. 

“Let’s say we have you and Lord Plume, Mrs Beachcomber and myself, and Donald and Ivanka Trump.” 

“I’m not getting into a boat with that dreadful man,” Lady C said. 

“That’s exactly the point,” I said. 

“You won’t have to. 

“So as I was saying, you and Lord Plume can cross together, then his Lordship comes back alone…” 

“Hang on,” she said, “isn’t this just a version of the farmer, wolf, chicken and bag of grain puzzle which also have to be rowed across the river without the wolf killing the chicken or the chicken eating the grain?”

“It’s similar,” I agreed, “but a bit more complicated.” 

“I’ve never understood why the farmer doesn’t just kill the wolf,” she said. 

“Then he could take the chicken over and come back for the grain.” 

“Perhaps that’s why Lord Plume thought you might find the suspicious husbands problem easier to relate to,” I suggested. 

“I’m only related to Lord Plume by marriage,” she said. 

“Let’s keep it that way,” I said, and we left it at that.