She remembered how her sisters’ laughter had rung out across the beach as if taunting her, how she had glanced above her sunglasses, watched Zoe and Jess throwing seaweed at each other, bowing her head back to her book before they caught her watching them, beads of sweat dripping from her forehead onto the page.

Why don’t you go and play with them, Lily? You’ve been reading all morning. You must be in need of stretching your legs?

Her mum had been sitting on a portable green camping chair surrounded by coolers filled with foil-wrapped sandwiches, apples, and bottles of fruit drinks. She had been reading Enormous Changes at the Last Minute by an author Lily had never heard of. Next to her, Lily’s dad had been sitting in an identical chair with a copy of The Times, which he had been reading—one column inch at a time—since they had arrived at the beach nearly two hours before.

Lily remembered looking over her shoulder to where the twins had resumed work on their sandcastle, an ambitious triple-story construction with towers, moats, and flags, the kind of project which Lily might once have attempted with help from her dad. She remembered shaking her head even as a part of her craved involvement.

Oh, do join in, Lily. It won’t be a proper summer holiday if my three musketeers don’t build the biggest sand palace on the beach.

She could hear now—as if the clocks had rewound and her mum was standing right next to her—the good humor in her voice. But back then Lily’s fingers had curled around the corners of her book.

My three musketeers. Her mum had called them that for years and Lily had often wondered whether it had once been an accurate description or whether it was something she’d said because she wanted it to be true.

I’m fine reading my book. I don’t want to build stupid sandcastles. It’s babyish.

Even all these years later Lily could hear the despondency in her voice, could sense the confusion that she didn’t know where her sadness had come from or why it had sneaked up on her like that.

There’s no need to be rude, Lily. Mum’s only offering a suggestion.

Her dad’s voice had been firm, unyielding. It was a voice he had only ever used on Lily, never on Zoe or Jess, a fact Lily had pointed out many times, only to be told she was imagining things.

Lying on the beach that day, Lily had thought about all the years she had wished for a sister to play with, all those weeks when her mum’s swollen stomach had offered such promise, before the news that there were to be two babies, not one. Lily had understood, even then, that after all that time together in her mum’s tummy, those twin babies would be close in a way Lily could never hope to be a part of.

Abandoning their sandcastle, Zoe and Jess had begun acting out Rapunzel: Jess the helpless princess, Zoe—as always—the handsome woodcutter come to rescue her.