The boy was not supposed to cross the station square.

Mara had told him that rule so many times it had become part of the morning, like the whistle of the kettle and the smell of toast.

Stay by the newspaper stand.

Keep your hood up.

Do not talk to strangers who ask too many questions.

And above all, if anyone asked about his mother, Theo was to say nothing until she came.

He had nodded with the serious face of a child trying to be brave for a grown-up.

But the cream envelope had fallen from the woman’s bag, and the rain was pushing it toward the gutter.

Theo saw it skitter across the wet stone.

He saw the gray-haired woman in the wool coat keep walking toward the taxi rank, one hand pressed to her ribs as if something inside her hurt.

People flowed around her with umbrellas and suitcases.

Nobody else noticed the envelope.

Nobody else saw the corner darken with water.

Theo looked back at the newspaper stand.

His mother was inside, paying the owner for two day-old rolls and a carton of milk.

Her back was turned.

He broke the rule.

“Ma’am!” he called.

The woman did not hear him.

Theo snatched up the envelope and ran.

His green dinosaur backpack bounced between his shoulder blades.

One glove was missing because he had dropped it somewhere between the bus stop and the station, and cold rain stung his bare fingers.

“Ma’am! You dropped this!”

The woman stopped beneath the great black station clock.

When she turned, Theo noticed first how still she was.

Not stiff, exactly.

More like someone who had been walking for years and had only just realized she was tired.

He held the envelope out with both hands.

“You dropped it.”

Her eyes fell to the envelope.

For a second, something like panic crossed her face.

Then she took it carefully, almost reverently.

“Oh,” she breathed.

“Thank you.

Thank you, sweetheart.

This is very important.”

The flap had loosened in the rain.

A photograph slipped halfway out.

Theo saw a young woman laughing in a red graduation dress, her hair blown across one cheek, a crescent moon necklace shining against her collarbone.

The square vanished around him.

“Why do you have my mom?” he asked.

The woman’s fingers tightened.

“What did you say?”

Theo pointed at the photograph.

“That’s my mom.”

The woman looked down.

The change in her face scared him.

She went pale so quickly that Theo thought she might faint.

Her mouth opened, but for a moment no sound came out.

“That is my daughter,” she whispered.

“Celia.”

Theo shook his head.

“My mom’s name is Mara.”

The woman lowered herself slowly until she was crouched in front of him.

“My daughter died ten years ago.”

“No, she didn’t,” Theo said, small but certain.

“She made my lunch this morning.”

The station seemed to fall silent around them, although the trains still breathed smoke beyond the glass doors and wheels still hissed on wet streets.

The woman stared at him with such desperate concentration that Theo took a step back.

“What is your name?” she asked.

He remembered the rules again.

Too late.

“Theo.”

“Theo,” she repeated, like the name mattered.

“How old are you?”

“Six.”

Her eyes flicked