The little kid raced past, flapping his wet hands before retrieving a frozen-yoghurt tub from a hot mom with a stroller. Harry thought about the gun. How to destroy fingerprints and DNA?

He sat on a concrete bench outside a Sunglass Hut, vaguely recognising some girls from his school strolling by. Harry made sure full privacy was switched on before searching. Google led him to a hobby site called The Forensic Enthusiast. The article claimed that regular chlorine bleach broke down all DNA in under an hour.

He read carefully, then checked the public comments below the article, to make sure there weren’t a bunch of people claiming the advice was bad. A few comments suggested alternatives, such as oven-cleaning foam, but the majority agreed that most criminals would use bleach, because it cost less than a dollar a bottle and was available everywhere.

Harry made a shopping list in his head as he strode towards Dollar Dominator at the far end of the mall: cleaning cloths, strong bleach, Ziploc bags, rubber gloves, strong plastic sacks.

Be meticulous. Clean the gun and dump it where it won’t be found for a long time. Throw out your backpack and everything inside it. You’ve got heaps of clothes, these are comfy running shoes but there’s probably tiny bits of explosive trodden in the sole and stuff so ditch them too … What else?

You can’t make one single mistake …

9 DAZED AND CONFUSED

Charlie had surrendered, but the cops still slammed her to the ground, causing a nosebleed. Her clothes had to go for forensic examination, so she wound up on a green vinyl bench in a police cell, naked beneath a disposable paper suit, with drips of blood down the front.

It was hard to keep time in the windowless cell, but Charlie guessed it was early evening when the door swung open. Her nose had finally stopped bleeding, but the clot felt like a thumb wedged up her nostril, and red-splattered napkins were balled all over the floor.

‘We need to have a conversation,’ a cop with an orange-dyed buzzcut said brightly.

She was at the tail end of her twenties. Chubby tattooed arms, black jeans and the sleeves of a plaid shirt rolled up, like she was about to chop wood.

‘I’m Officer O’Banyon,’ the cop said, gum in her mouth. ‘Don’t need to cuff you, do I?’

She took Charlie one floor up, then offered anything you like from the vending machine, as if that was the deal of the century. The interview room had been prepped. Files waiting on the table, a stack of disposable cups and a tatty plastic water jug with cling wrap stretched over the top.

‘Take a chair,’ O’Banyon said.

The officer’s movements were all floaty, her voice easy. Trying to play the chilled big sister.