Either way, the detective’s best guess now was that Harry and Morag would go back to either his place or hers, and spend the evening commiserating about the lost fortune. He already had Carl Hoskins in an unmarked car sitting outside Morag’s house, and he himself would make a flying visit to Harry’s flat at Walton-on-Thames.

What about Deepak? Although Gillard was convinced that Deepak’s fraudulent actions were connected to Mrs Roy’s murder, the DNA on the murder weapon might well have an innocent explanation. Certainly his alibi from his girlfriend, Victoria, was stronger and more detailed than the one Jason Waddington had tried to use, and since yesterday had been backed up by the cell-site location and calling record of his phone. If Deepak had murdered Mrs Roy, then someone else was making calls on his phone from Victoria’s house at the same time.

Right from the beginning, there had been lots of bits in the case that did not fit together. Most puzzling of all was a good proper motive. And that’s why Gillard was drawn again to this arranged marriage.

The detective parked his car on the road outside the flats, and made his way towards the entrance. The reception area was unstaffed, and he had no intention of announcing his arrival by pressing Harry’s buzzer. He only had to wait a minute or two to get in to the block while someone else was leaving. Gillard, still famished, helped himself to an apple from a complimentary bowl of fruit as he walked towards the lift. He descended to the basement, and emerged into the private car park. Harry’s car was there and Gillard’s hand on the bonnet detected the warmth that confirmed its recent use. He returned to the lift, finishing the apple as he hit the button for the penthouse floor. He emerged into a corridor carpeted in hues of wheat and lined with dark textured wallpaper that would give a child nightmares.

He remembered Gabby Underwood telling him that there were only two flats on this level, but he couldn’t remember which was Harry’s. However he did recall her saying that Harry’s flat gave a great view across the river. Gillard made his way softly along the carpet to the window at the corridor end. The Thames lay below and to the left, while a full moon slid palely behind a wisp of cloud.

Gillard made his way back to the large, dark door which he presumed led to Harry Roy’s flat. He could hear music, faintly, from within. A woman said the word ‘bridesmaid’, and then laughed. He knew that infectious laugh. Morag. He also heard a faintly familiar pop tune, perhaps uplifting for a man whose mother had recently been murdered, and who had been depressed. He could discern Harry’s voice within, sounding plaintive, and another woman’s answer, not Morag. He could not tell what she said until one phrase: ‘Talk it through, Harry. There’s no point skulking out there.’ Gillard then heard a bang. His finger was poised above the doorbell, but he decided not to press.