Amy spent the mornings below decks with her tutor, Grace Wainwright, and the rest of the time was hers to enjoy. Grace, a serious and slightly nervous young woman from Leeds, had been strict at first, but the gentle lapping of the water against the hull and the warm scented air of the Greek islands had soon worked their magic on her. With each day the lessons grew shorter, the lines on Grace’s face softened and the light shone more brightly in her eyes.

This morning they had finished lessons at eleven o’clock. Grace had sighed and pushed away the book of French grammar they had been struggling over, then stared longingly out through a porthole at a perfect disc of blue sky.

‘That’s it for today,’ she had said. ‘Don’t tell your father.’

Amy stepped up on to the bulwark and peered into the water. It was rich turquoise and as clear as glass. She could see the anchor chain angling down, surrounded by a school of tiny fish that glinted as they swam in and out of slanting, golden shafts of light.

She flexed her long thin body and prepared to dive in.

‘Shouldn’t you be studying?’ It was her father’s voice, but Amy pretended not to hear him, stretched up on to her tiptoes, bent her knees and sprang lightly off the edge of the yacht. For a moment she was suspended in space, the clear blue waters of the Aegean spread out beneath her like a glittering carpet. Then she arced down and the sea raced up to meet her. It was a perfect dive; her body barely disturbed the surface, and the next thing she knew she was down with the fish in a cloud of silver bubbles. She bobbed to the surface and swam away from the yacht towards the nearby rocks that formed a wall around the little natural harbour they were anchored in. After a while she turned and looked back to see her father standing at the rail waving to her.

‘I say! Amy! Should you not be studying?’ he called out.

‘Grace had a headache, father!’ she called back, lying easily. ‘We’re going to carry on later when it’s not so hot.’

‘Very well… See that you do.’

Her father tried to be severe with her, but in this weather, in these beautiful surroundings, with such a lazy lifestyle, he found it as difficult as Grace to maintain any sense of discipline. Besides, Amy thought, diving down and scattering a shoal of snappers, she had always known how to get round him. It was harder for Mark, her older brother. If there had been a fire at his school, he would have instantly been moved somewhere else and there would have been no question of him coming to Greece.

Their father, Sir Cathal Goodenough, was a sailor through and through. He had joined the navy at sixteen and served under Jellicoe at the Battle of Jutland, before being made an admiral himself in 1917. He had been knighted for his services in the Great War, protecting convoys from submarine attack in the Atlantic. When his wife died he had left the navy, but the sea was in his blood. He hated to be on dry land, and at any opportunity he would be on one of his three yachts: the Calypso, which was moored in the West Indies; his racing yacht, the Circe, which was kept in Portsmouth; and this one, his most prized vessel, the Siren, which overwintered in Nice.