He took a step back, clearly unsettled by the vehemence of her reaction. He said something to the helmsman, and the boat veered towards a narrow wharf where a couple of launches were moored. ‘Caroline, I didn’t mean to offend you,’ he said as she moved to the side of the boat nearest the wharf.

‘And that’s supposed to make me feel better?’ The boat pulled alongside and, without waiting for the helmsman to tie up, Carol jumped ashore. ‘Don’t call,’ she threw over her shoulder as she marched up the wharf towards a flight of stone steps. Her whole body was trembling as she reached street level. She checked that he wasn’t following her, then stepped to the kerb to hail a cab.

She hoped she hadn’t wrecked the operation. But she hadn’t been able to think of anything else to do. His suspicions had come out of a blue sky, and she’d allowed herself to sink into complacency, so she hadn’t been quick enough on her feet to talk him round. She sank back into the cab seat and prayed she’d got it right.

The small plane from Bremen to Berlin was configured with a single seat on one side of the aisle, which meant Tony could look with impunity at the crime scene pictures Berndt had handed him at police headquarters in Bremen. He took them out of the envelope with some trepidation. He wasn’t looking forward to seeing the mutilated corpse of a woman he had been acquainted with. There was always something bizarrely intimate about poring over photographs of the dead, and he didn’t want such familiarity with someone he had known in life.

In the event, it wasn’t as bad as he had anticipated. The harsh glare of the flash had made the images of Margarethe’s body impossible to connect with the lively woman he remembered. He studied the photos in detail, wishing he had brought a magnifying lens with him. To the naked eye, there seemed to be no significant differences between the body of Margarethe and Geronimo’s other victims. They were all laid out in similar fashion, their clothes cut away to form an improbable table cover beneath them, the incongruous wound left by the scalping almost identical.

He was about to give up his perusal of the photographs when something caught his eye. There was something odd about one of the ligatures that bound Margarethe’s limbs to the table legs. He peered harder, trying to make out the details. The knot looked different from the others.