On the day that Crab was sentenced, Brock received a brown-paper parcel in the mail containing the Schwitters and a carefully written note from Walter, gifting him the picture in compensation for Brock’s ruined suit. Ever since, Brock had regarded the little collage as an icon, a condensed statement of his own calling, gathering the discarded residue of people’s lives and making out of it some kind of pattern and sense.

Brock folded the letter and tucked it into the management report to mark the place he’d reached, then turned his attention to the third document on the table, every page of which he’d memorised over the weekend. It was a file marked Metropolitan Police, Case File Summary: Abductions of Aimee Jennifer Prentice and Lee Celine Hammond. He turned to the pictures of the missing girls, although they were already imprinted in his mind; Aimee with a cheeky lopsided grin and Lee, dreamy and pensive, as if she could sense the onset of puberty inside her slight body.

Pinned to the cover of the report was the memo confirming the formation of a Major Enquiry Team, headed by Detective Chief Inspector David Brock, which would take control of the case as from 0800 hours on Monday October 13. Brock checked his watch. Two hours. Time to go. athy drove slowly down the clogged artery of Kingsland Road in Shoreditch, part of the stream of sullen Monday morning traffic splashing cold puddles over the legs of huddled bus queues. She could hear the howl of a police siren somewhere up ahead, and on the radio she picked up the first news reports of another missing girl, the third child abducted from her home in east London in recent weeks.

She made a turn into Lazarus Street and found herself hemmed between the dark brick walls of warehouses under conversion to offices, studio flats and uncertain investment opportunities. Two small girls burst out of a side alley, school bags bouncing on their shoulders, black faces bright with glee, and Kathy stopped to let them pass.