But he knew the distance already, from maps: almost eighty kilometres. So he could reverse the whole calculation, and use it to verify his altitude: the lowest point from which he could see land would be five hundred metres. He’d drive a stake into the ground to mark the spot. He turned towards the centre of the island, the black peak just visible above the coconut palms that rimmed the beach. It sounded like a long climb, especially if he had to carry Madhusree most of the way.

‘Do you want to go see Ma?’

Madhusree pulled a face. ‘No!’ She could never have too much of Ma, but she knew when he was trying to dump her.

Prabir shrugged. He could do the experiment later; nothing was worth a tantrum. ‘Do you want to go swimming, then?’

Madhusree nodded enthusiastically and clambered to her feet, then ran unsteadily towards the water’s edge. Prabir gave her a head start, then pounded across the sand after her, bellowing. She glanced at him disdainfully over her shoulder, fell down, stood up, continued. Prabir ran rings around her as she waded into the shallows, the soles of his feet slapping up water, but he made sure he didn’t get too close; it wasn’t fair to splash her in the face. When she reached little more than waist height, she dropped into the water and started swimming, her chubby arms working methodically.

Prabir froze and watched her admiringly. There was no getting away from it: sometimes he felt the Madhusree-thing himself. The same sweet thrill, the same tenderness, the same unearned pride he saw on his father’s and mother’s faces.