I second that. Imagine if we got back to 2048 without Kwesi? Ama would never speak to us again. GMT stays in The Beanstalk with the Leaplings who are still eating like they haven’t eaten for days and they haven’t, not since the robots abandoned the centre and all the machinery stopped and they thought they’d die of starvation.

MC2, Big Ben and I are walking up the spiral staircase to the first floor when we hear the music.

It’s faint at first, like you’re imagining it in your head, but as we continue up the stairs it gets louder, till we’re taking two steps at a time like athletics training. I’ve heard music like this before, at the leap day celebration: that 1924 music Noon likes and she and Ama went crazy in their dancing, all arms and legs. Noon! We stop outside a door at the top of the stairs. Or rather, I stop, but MC2 tries to open it, which is impossible because it doesn’t have a handle.

‘There’s a code lock,’ I say, and he taps in 1900MM. A second later, the door clicks open and the music stops.

‘Careful,’ I say. ‘It could be a trap.’

We push the door in slow motion. The first thing we see is a large black wall covered in numbers and letters sprayed on like graffiti. But they’re not flat against the wall. It’s like the wall has come to life and is breathing. I squint my eyes and make out some of the symbols. E=MC2, 2100 rotated all different angles, upside down, inside out, back to front. In the left-hand bottom corner, an unmistakable L with an infinity sign weaving in and out of it like a snake. Next to it, the thick black outline of a boy. Inside the outline, a tall black boy with round glasses, big ginger hair, white-and-black clothes like MC2 and an infinity tattoo on his left hand.

I stare at the painting of the boy until it blinks! Slowly the painting that is a boy comes out of the wall towards us. Big Ben takes a step back. MC2 swears under his breath and holds up his left fist like he’s giving the Black Power salute in Mexico City in 1968. His voice sounds odd when he speaks, like he has a sore throat.

‘The Squared missed a beat when you went phone-dead.’

The boy looks at him like he’s looking twice, first through his eyes, then through his glasses. Very slowly, he holds up his left fist. They touch fists, clap palms, snap fingers till it sounds like a rap. Then they make all kinds of shapes with their hands like they’re sculpting air. A sign dance. MC2 turns to face us.

‘Elle. Big Ben. KWESI. Kwesi. ELLE. BIG BEN.’