Updark had nothing on him! There was no evidence to link Dyer with Marvar’s discovery – only these eleven sheets of A4.

Leandro looked up, startled. ‘Dad, are you all right?’

‘Yes, yes …’ He was rereading the first page of his interview. He did not need Astrud’s photograph to warn him. He had to hide this – or destroy it. The information must not be found in the house.

Dyer looked up from the page, white against the table, to his son. He didn’t want to infect Leandro with his relief, his fear.

Leandro inspected him with touching tenderness. ‘I hope you haven’t caught my cold.’ He bit his lip. ‘I may have given it to Samir.’

Dyer leaned forward. ‘You’ve seen Samir?’

‘No, no, not today, he didn’t come to school. Mr Tanner thought it was his injury, but Dad, it wasn’t, he was walking fine. I bet you anything it was that flu I had. He wasn’t feeling well at the sleepover, I could see.’

After Leandro went to bed, Dyer made himself a cup of tea. He added milk, and as he closed the fridge he was arrested by a memory of Rustum Marvar standing in the exact spot where he himself now stood.

Marvar had been staring at Leandro’s Pelé magnet, his face, everything about him, altered from a moment before.

From two feet away, Dyer absorbed the image of the Brazilian footballer on the fridge door. Then the slow thought came to him. What if Marvar’s eyes were fastened not on Pelé, but on the square of yellow paper protruding from beneath?

‘So that’s what they’re called!’

Marvar had stopped on the towpath and thrown back his head in laughter when Dyer told him.

‘Post it. You mean, like a letter. Me to you?’

But in the very next moment Marvar appeared conflicted, as though he had committed an error. Dyer’s heart had reached out to him. He recognised the awkward emotion felt by someone who had suffered tragedy, when people caught them laughing.

Dyer stepped closer to the fridge. There seemed to be an unfamiliarity about his handwriting on the post-it note. His eyes scanned the names and the numbers that he had jotted down – for Paula next door; Domino’s pizzeria; Magda, the Polish cleaner; the landlord’s management company in Summertown …

Then he saw it.

Squeezed in between the letters and figures that Dyer had written, a single word stood out. It had been scrawled in a strange hand using his propelling pencil. Each capital letter as bold as an initial branded on a tennis ball.

‘BOOMERANG’.

An apparently insignificant thing can be of huge importance, life had taught Dyer. He waited until the last chime of midnight faded into the Oxford darkness. He checked once again that Leandro was asleep, and then he put on an extra jersey and a black wool balaclava that he never wore, and stepped outside.