Mortlake Crematorium is a low-rise art deco masterpiece, right on the southern edge of the Thames near Chiswick Bridge. It has become a favoured place for Hindu cremations because of the possibility of spreading the ashes of the deceased in London’s great river, the nearest approximation to the Ganges available locally. After a chorus of pleas from the family, the cremation of Mrs Tanvi Roy was finally taking place ten days after her death, following approval from the coroner that all forensic samples that might be required had been taken.

Gillard and Claire, stuck in traffic in the rain and fearing they would be late, parked at Teddington and took the overground train to Mortlake for the last few miles. Approaching on foot, they saw the mourners clustered by the gates, a great sea of white clothing and colourful umbrellas, gathered around three or four black limousines. Claire, in a conservatively cut white knee-length dress with matching pashmina and peep-toe shoes, was a more fashionable figure than Gillard, whose cream trousers had just been splashed by a passing taxi.

At the gates they spotted Kiara, who stood out from the crowd in a dazzling feathered creation and stiletto-heeled white boots.

‘My God,’ Claire said to Gillard. ‘I’ve heard about that dress. It’s apparently made from sustainably-collected swans’ down. Retails on her website for £7,000.’

‘Sustained plucking presumably leading to persistent hissing,’ he replied.

Kiara approach them and thanked them profusely for coming. ‘We’ve finally got a chance to say goodbye to her. It seems such a long time ago that we heard the awful news, yet it was less than two weeks,’ she said. ‘All our lives have changed irretrievably because of this one act of senseless violence.’ A woman in a sari approached with a brass dish heaped with bright red powder. Kiara dextrously anointed both the detective’s foreheads with the vermilion dot, or bindi, which denotes blood sacrifice.

Gillard had done his homework on what was expected of him. He was surprised by how little a Hindu funeral differed from the Christian tradition. There would be an open coffin, prayers, and a farewell. Traditional Hindu practice stipulated a cremation open to the sky, as would occur in India. Though the Court of Appeal had ruled that such a practice could be allowed in Britain, no crematorium as yet offered a retractable roof over the cremation chamber, which would allow the process to meet both Hindu custom and UK health and safety rules.

Mrs Roy’s casket arrived garlanded with chains of orange and white marigolds, and each of her children carried a framed black and white photograph of their mother with them as they walked into the building. The detectives were not there purely to pay their respects as representatives of the police, but to watch the mourners, and to further the investigation. They took their seats towards the back of the chapel, and turned to watch the others filing in.

Gillard mentally ticked off those he knew: Simon and Prisha with her daughter Indigo, Harry, flanked by Morag on one side and Kiara on the other, and Zayan Lal with Philippa Boswell on his arm, his other hand busy on his phone. Unsurprisingly, there was no sign of Deepak, but Gillard did recognise Johnny Lam, talking to the family lawyer Vikram Vaj. The retired Indian judge, L. P. Gosht, seemed to be at the centre of a large convention of elderly men, almost all of whom turned to look at a set of new arrivals.