“Sadie, stop!” I’m almost too incredulous to speak. “You can’t do this! You can’t go around spying on everyone in my life!”

“Yes, I can,” she says, opening her eyes wide as though it’s obvious. “I’m your guardian angel. It’s my job to watch out for you.”

I stare back at her, flummoxed. The plane engines begin to roar as we start our descent, my ears begin to pop, and there’s a slight heaving in my stomach.

“I hate this bit.” Sadie wrinkles her nose. “See you there.” And before I can say anything else, she disappears.

Uncle Bill’s mansion is a longish taxi ride from Nice Airport. I stop for a glass of Orangina in the village cafe and practice my schoolgirl French on the owner, to Sadie’s great amusement. Then we get back in the taxi and head the final stretch to Uncle Bill’s villa. Or complex. Or whatever you call a massive white house with several other houses dotted around the grounds and a mini-vineyard and a helicopter pad.

The place is staffed pretty heavily, but that doesn’t matter when you have a French-speaking ghost by your side. Every member of staff we come across is soon turned into a glassy-eyed statue. We make our way through the garden without being challenged, and Sadie leads me swiftly to a cliff, into which steps are cut, with a balustrade. At the bottom of the steps is a sandy beach and, beyond that, endless Mediterranean.

So this is what you get if you’re the owner of Lingtons Coffee. Your own beach. Your own view. Your own slice of sea. Suddenly I can see the point of being immensely rich.

For a moment I just stand shading my eyes from the glare of the sun, watching Uncle Bill. I’d pictured him relaxing on a sun lounger, surveying his empire, maybe stroking a white cat with one evil hand. But he’s not surveying anything, or relaxing. In fact, he’s not looking as I imagined him at all. He’s with a personal trainer, doing sit-ups and sweating profusely. I gape, astonished, as he does crunch after crunch, almost howling with pain, then collapses on his exercise mat.

“Give… me… a… moment…” he gasps. “Then another hundred.”

He’s so engrossed, he doesn’t notice as I quietly make my way down the cliff steps, accompanied by Sadie.

“Per’aps you should rest now?” says the trainer, looking concerned as he surveys Uncle Bill. “You ’ave ’ad a good workout.”

“I still need to work on my abs,” says Uncle Bill grimly, clutching his sides in dissatisfaction. “I need to lose some fat.”

“Meester Leengton.” The trainer looks totally bemused. “You ’ave no fat to lose. ’ow many times must I tell you thees?”

“Yes, you do!” I jump as Sadie whirls through the air to Uncle Bill. “You’re fat!” she shrieks in his ear. “Fat, fat, fat! You’re gross!”

Uncle Bill’s face jolts with alarm. Looking desperate, he sinks to the mat again and starts doing more crunches, groaning with the effort.

“Yes,” says Sadie, floating about his head and looking down with disdain. “Suffer. You deserve it.”

I can’t help giggling. Hats off to her. This is a brilliant revenge. We watch him wincing and panting a while longer, then Sadie advances again.

“Now tell your servant to go!” she yells in his ear, and Uncle Bill pauses mid-crunch.

“You can go now, Jean-Michel,” he says breathlessly. “See you this evening.”

“Very well.” The trainer gathers up all his pieces of equipment, brushing the sand off them. “I see you at six.”

He heads up the cliff steps, nodding politely as he passes me, and heads toward the house.

OK. So now it’s my turn. I take a deep breath of warm Mediterranean air and start to walk down the rest of the cliff steps. My hands are damp as I reach the beach. I take a few steps over the hot sand, then just stand still, waiting for Uncle Bill to notice me.

“Who’s…” He suddenly catches a glimpse of me as he comes down onto the mat. Immediately he sits up again and swivels around. He looks utterly stupefied and slightly ill. I’m not surprised, after doing 59,000 sit-ups. “Is that… Lara? What are you doing here? How did you get here?”

He looks so dazed and drained, I almost feel sorry for him. But I’m not going to let myself. Nor am I going to be drawn into small talk. I have a speech to make and I’m going to make it.

“Yes, it is I,” I say, in the most imposing, chilling voice I can muster. “Lara Alexandra Lington. Daughter to a betrayed father. Great-niece to a betrayed great-aunt. Niece to a betraying, evil, lying uncle. And I will have my vengeance.” That bit was so satisfying to say, I repeat it, my voice ringing across the beach. “And I will have my vengeance!”

God, I would have loved to be a movie star.

“Lara.” Uncle Bill has stopped panting by now and almost regained control of himself. He wipes his face and pulls a towel around his waist. Then he turns and smiles at me with that old suave, patronizing air. “Very stirring stuff. But I have no idea what you’re talking about, nor how you got past my guards-”

“You know what I’m talking about,” I say scathingly. “You know.”

“I’m afraid I have no idea.”

There’s silence except for the waves washing onto the beach. The sun seems to be beating even more intensely than before. Neither of us has moved.

So he’s calling my bluff. He must think he’s safe. He must think that the anonymous agreement protects him and no one will ever be able to find out.

“Is this about the necklace?” Uncle Bill says suddenly, as though the thought has just struck him. “It’s a pretty trinket, and I can understand your interest in it. But I don’t know where it is. Believe me. Now, did your father tell you, I want to offer you a job? Is that why you’re here? Because you certainly get marks for keenness, young lady.”

He flashes his teeth at me and slides on a pair of black flip-flops. He’s turning the situation. Any minute now he’ll be ordering drinks and somehow pretending this visit was all his idea. Trying to buy me, trying to distract me, trying to turn everything his own way. Just like he’s done all these years.

“I’m not here about the necklace, or the job.” My voice cuts across his. “I’m here about Great-Aunt Sadie.”

Uncle Bill raises his eyes to heaven with a familiar exasperation. “Jesus Christ, Lara. Will you give it a rest? For the last time, love, she wasn’t murdered, she wasn’t anything special-”

“And the painting of her that you found,” I carry on coolly. “The Cecil Malory. And the anonymous deal you did with the London Portrait Gallery in 1982. And the five hundred thousand pounds you got. And all the lies you told. And what you’re going to do about it. That’s why I’m here.”

And I watch in satisfaction as my uncle’s face sags like I’ve never seen it before. Like butter melting away under the sun.

It’s a sensation. It’s front-page news in every paper. Every paper.

Bill “Two Little Coins” Lington has “clarified” his story. The big, one-to-one interview was in the Mail, and all the papers jumped on it immediately.

He’s come clean about the five hundred thousand. Except, of course, being Uncle Bill, he went on at once to claim that the money was only part of the story. And that his business principles could still be applied to anyone starting out with two little coins. And so actually the story isn’t that different and, in a sense, half a million is the same as two little coins, it’s simply the quantity that’s different. (Then he realized he was on to a loser there and backtracked, but too late-it was out of his mouth.)

For me, the money really isn’t the point. It’s that finally, after all this time, he’s credited Sadie. He’s told the world about her instead of denying her and hiding her away. The quote that most of the papers used is: “I couldn’t have achieved my success without my beautiful aunt, Sadie Lancaster, and I’ll always be indebted to her.” Which I dictated to him, word for word.