My 13-year-old took a dishwashing job to save for a bike. Six months later there was still no bike — then his boss rang me: “Do you know what he does with every paycheck?”

Almost there.

At first I believed him completely.

Then three months went by. Four. Five. Six.

And still no bike.

So I did the sums, one night, on the back of an envelope, because I am a person who does sums on the backs of envelopes.

He was earning enough every Saturday that he should have had that bike by about the end of the third month.

So where was it going?

I tried not to worry. Maybe he had gone off it. Maybe there was a girl. Maybe he was saving for something else — a surprise, for my birthday, which was in the September.

Then one night I walked past his room at about eleven and the light was still on and the door was half open.

He was sitting on the floor with his back to the bed, counting a thick stack of cash.

Far more than I expected. Far more than one Saturday.

The second he saw me in the doorway, his whole face changed.

He swept it all together in one go, shoved it into his school rucksack, and zipped it shut.

I said: what are you doing?

He said: nothing.

I looked at the rucksack.

I said: was that your bike money?

He nodded, fast. Too fast.

I said: that looked like a lot.

And he said: Gus pays me in small notes. It just looks like more than it is.

And then he smiled at me — a nervous smile, a smile I had not seen on him before — and said:

I’m getting close.

PART 2

Something was wrong. I knew it on the landing that night.

And I did not push.

He was thirteen. He had lost his father. I told myself he was entitled to some things that were his.

So I told myself there was an innocent explanation, and I went to bed and did not sleep.

A few weeks later, that got much harder to believe.

Finn always came home from the diner at about six.

That Saturday, six came and went. Then seven. Then half past.

His phone went straight to voicemail, four times.

By the time the back door finally opened it was nearly eight, and I had my coat on and my keys in my hand.

I ran into the hallway.

And then I stopped.

His trainers were caked in mud up to the laces. His jeans were soaked to the knee. One sleeve of his jacket was torn right down from the shoulder.