A burst of black smoke went up and some of the firemen were already wearing breathing apparatus.

‘Better get further back – a muggy night like this will make the fumes hang about low down.’

There was a warning shout as the shop window fell out and crashed onto the pavement, and, as the glass shattered, the outside air hit the flames inside with a roar.

There had been no reply from Wang’s landline, or his mobile, so a patrol had been sent out to his home. Simon stood watching, waiting, anxious, various possible scenarios running through his head. The call interrupted them.

‘We’re outside 14 Marmion Road, guv, and we haven’t been able to raise anyone, there are no lights on, curtains are drawn, there’s no car in the drive or parked.’

‘Any neighbours come out or look through a window?’

‘No, but the house next door is empty with a Sold sign and then it’s a corner, with a side road, so chances are nobody saw anything.’

‘Houses opposite? Come on, you shouldn’t need me to tell you this.’

Half an hour later, they reported that one neighbour was about but was new and didn’t know anyone, another said she thought the Wangs were early risers but she didn’t know any more.

‘I’ll be over. Stay where you are.’

‘We’re supposed to be off in ten, guv.’

‘I didn’t hear that.’

The patrol car was parked up, uniform in it looking bored.

Serrailler opened the door and beckoned them out. ‘And this takes as long as it takes, have you got me?’

He turned his back on them and went up the drive of number 14. The curtains were all drawn together. He pushed open the letter box but there was a felt cover on the inside, so he could not see into the hall; he put his ear to it and heard no sound at all.

‘Round the back.’ A well-tended garden, even in winter, shrubs neatly trimmed, a path which had no moss or dirt on its surface, a small summer house at the end, locked but with folded deck-chairs and a small table visible through the window. The glass back door of the house that opened onto a strip of terrace was also curtained. They returned to the front.

‘We need to get inside.’

‘I’ve got a strong shoulder, guv.’

‘Fine, but just before you apply brute force, have either of you looked for a spare key? Under the mat, a plant pot?’

The three of them split up to search and it was only a couple of minutes before the big man shouted. There was a low wall between the terrace and the grass, made to look like a rockery and he was standing beside it, holding up a key in one hand, a grey lump in the other. ‘One of them phoney stones with a space inside – you can spot them a mile off.’