‘No, Sir,’ said DI Mathers. ‘Harry Graham had multiple stab wounds, too many to have been self-inflicted. And we found the knife upstairs in the boy’s bedroom. Mr Graham was downstairs.’ DI Mathers followed her boss’s eyes into the room behind her, towards the two children building Lego towers. ‘So we’re pretty sure there’s a third party involved.’

‘This monster went upstairs to find the children?’ asked Chief Superintendent Barker.

DI Mathers shrugged. ‘That’s what we need to find out.’

Steve unbuttoned his jacket and placed his hands in his pockets. ‘So what are we dealing with here, Bloom? Is this some nutter killing the families of players who fail a game?’

Bloom shook her head. She didn’t know the answer to that. ‘Have the children said anything?’

DI Mathers glanced through the window and shook her head. ‘The Chief Super wanted me to wait for you.’

‘Let’s go then.’ Bloom shook hands with Barker again and followed Mathers into the next-door room.

‘Wow, Fred,’ said DI Mathers. ‘That’s a great tower.’ She sat on the edge of the seat previously occupied by her colleague, who had now left, and turned on the videorecording equipment with a remote control. ‘Are we OK to have a little chat while you two are building?’ Bloom could tell immediately from the warmth of her tone and her friendly expression that Mathers knew what she was doing. ‘This is Dr Bloom.’

‘Hi, Fred. Hi, Julia. I’m Augusta.’ Bloom sat down. The boy had dark hair and a more olive complexion than his fair-haired younger sister. He wore jeans with a red T-shirt that had an aeroplane on the front. Julia wore pink leggings with a purple dress covered in unicorns.

‘Your name is August,’ said Julia with a giggle of delight.

‘That’s right. And yours is like July,’ said Bloom.

The little girl frowned.

‘Augusta is like August. Julia is like July.’

Julia beamed at her. ‘Yes, like July!’

‘Her birthday is in July.’ Fred was looking at Augusta with wide eyes.

‘Maybe that’s why your mummy and daddy picked the name.’

Fred looked at his sister, then back at Bloom. ‘When’s your birthday?’

Bloom smiled. ‘Can you guess?’

‘August,’ both children said together.

DI Mathers winked at Bloom, then began gently probing the children for details. She started with what they’d had for breakfast yesterday morning and who had been there.

‘Weetabix and just Daddy,’ said Fred.

Then she coaxed them towards lunchtime, when their father had been attacked while making cheese sandwiches with slices of apple on the side. Bloom sat listening, watching and hoping they didn’t hit a brick wall of silence anytime soon.

‘Fred, where were you and Julia when your daddy was making lunch?’ asked Mathers.

The young boy paused, holding a yellow rectangular block above his tower. ‘We were helping.’ He put the yellow block in place and pushed it firmly down.