Dyer looks down at the long overcoat he is wearing, and explains. ‘Pertence a um amigo.’

Miguel, who was born in Madeira, is a plump man with two strands of white hair across his skull. After the ritual exchanges about the uncle in Funchal, the granddaughter at Phil & Jim, Dyer orders a cup of tea and a rice cake.

A table is free by the pillar. Dyer takes off the heavy coat and hangs it over the back of the cane chair. A button is missing from the sleeve, and he thinks of Marvar’s fingers on Port Meadow, fretting.

Settled in his chair, Dyer unzips his shoulder bag. First, he draws out the eleven pages of A4 which Leandro had returned to him, and sets these to one side. Then he pulls out the plastic Ziploc sandwich bag containing the corrugated green folder, lays it on the table and opens it.

From the folder he extracts a square of yellow paper, two inches by two – which Marvar must have ripped off a pad, since adhered to the back are two further post-it notes, both blank.

Dyer stares at this meteorite which has fallen into his scared hands. He holds it up, and struggles to make sense of what Marvar, in blue biro, has set down on both sides in meticulous, close-spaced, small writing.

Light from a plastic-shaded lamp falls on a jumble of figures and letters, some Greek, others Roman, some capitalised, others not, and on the reverse, beneath more calculations – qualities and names of the minerals to be used as lasing materials? – a sentence on its own: Otto Hahn – ‘contrary to God’s will’?

This terrible knowledge, which might set fire to the atmosphere, to water – or give us sun on earth. This is the original. There is no other copy. Buried in the sand for Dyer to find.

It was inescapable and inevitable as biography that Dyer should be the recipient. Any pai de santo peering into his shallow basket of cowrie shells could have told him: it was not by accident that Marvar had brushed up against Dyer’s life. Marvar was like the surf which came in when he was running along the beach to Leblon, sometimes engulfing his legs, tugging him back, wet; a wave larger than all the others, unannounced, able to roll you over and over.

Dyer pictured Marvar writing it carefully down, his taut face. He must have buried it on Sunday morning before collecting Samir from the Asselins. Marvar had remembered Dyer’s schoolboy story and had pinned his hopes on it.

He hears the sound of seashells being sifted. ‘He has given you this knowledge for you to decide, because he was unable to decide himself.’