“Well, I say ‘stake.’ ” Raymond begins to chuckle again. “He didn’t put any money in. It was more like a ‘contribution.’ ”

“Contribution? What contribution?”

I’m half-hoping to hear that my dad was the one who had the blinding insight that kick-started the whole invention.

“Your dad gave them the pad of paper they wrote it on.”

“Paper,” I say, deflated. “Is that all?”

“It was enough! They joked about it. Corey and Brent were desperate for something to write on. Your dad had a big sketchbook. He said, ‘Well, if I give you my sketchbook, I want in on this,’ and Corey said, ‘You got it, Graham. You’ve got one percent.’ I mean, we were all joking. I helped them sketch out their ideas. It passed a few evenings.” Raymond takes another glug of iced tea. “But then they made the spring. The money started pouring in. And as far as I know, Corey stuck to his word. Sent your dad a dividend every year.”

I’m dumbstruck. My dad has a stake in a spring? OK, I take it back. This is a pretty good story.

“I had an inheritance around that time,” Raymond adds, “so I put some real money in. Set me up for life.”

“But how can a spring make so much money?” says Suze skeptically. “It’s just a piece of curly wire.”

That’s exactly what I was thinking, only I didn’t want to say it.

“It’s a kind of folding spring.” Raymond shrugs. “Useful thing. You’ll find it in firearms, computer keyboards…you name it. Corey and Brent were smart. Corey had a gun; he did some hunting. They’d take it apart in the evenings, play around with the spring-loading mechanism. It gave them ideas. You know how it is.”

No, I don’t know how it is. I’ve sat around loads of times with Suze, and we’ve taken plenty of things apart, like makeup kits. But I’ve never invented a new spring.

I suddenly understand why Dad was always so interested in my physics report. And why he used to say, “Becky love, why not go into engineering?” and “Science is not boring, young lady!”

Hmm. Maybe he had a point. Now I half-wish I’d listened.

Ooh, maybe we can train up Minnie in science and she’ll invent an even more advanced spring and we’ll all be squillionaires. (When she’s not winning the Olympics at show jumping, of course.)

“When they got back from the trip,” Raymond is saying, “they hired a lab and developed it properly. Four years later they launched it. At least, Corey launched it.”

“Only Corey? Why not Brent?”

Raymond’s face kind of closes up. “Brent bowed out after three years,” he says shortly.

“Three years? What do you mean, before it launched? So he didn’t make any money?”

“Not to speak of. He pretty much just signed away his rights.”

“But why on earth would he do that?” I demand in horror. “He must have known it had huge potential.”