‘It’s not hard,’ Rosie said. ‘Millions of cars with old battery packs get scrapped. The batteries are too weak to put in another car, but they still make low-drain backup batteries for solar-power systems. The scrapyards have to pay to dispose of the batteries, so they let me grab as many as I want.’

‘We got lucky having you and Vern as neighbours,’ Harry said brightly. ‘I could barely change a light bulb when we first moved out of the city. You’ve taught us everything.’

‘You help us too,’ Rosie pointed out. ‘Charlie takes our parcels and runs all our errands in town. You helped Vern lift the new air-conditioner on to our roof. And the people who owned that house before you were a nightmare. Growing weed and partying all hours …’

This jarred with Harry, because Vern and Rosie didn’t know about the modding lab.

‘Think I hear Vern,’ Harry said as the garage door rattled.

Vern usually took a few moments to take off his boots, but he came straight through to the kitchen looking flustered.

‘There’s two pickups racing up the hill,’ he said breathlessly.

Harry grabbed his phone to check the CCTV cameras they’d set up together.

‘Already checked. The cameras are out,’ Vern said as he picked up an old wall-mounted telephone with a long curly cord. ‘Landline’s cut too.’

Harry thought fast. There’s no phone signal out here in the mountains. The CCTV works on our shared WiFi network and Vern’s landline phone is a different system. So two different systems have stopped working, and it isn’t a power failure because the air-conditioning is humming …

‘Internet seems to be down too,’ Harry said, looking at his phone.

‘It’s gotta be zombies in them pickups,’ Rosie said, looking frightened.

‘Cutting phone lines seems too organised for zombies,’ Harry said.

‘Now that the cops reverse zombies when they’re caught, they’re selecting mods that leave them with better survival skills,’ Vern said. ‘We watched a PBS documentary about it a few weeks back.’

‘It’s called a three-fourteen-B mod,’ Rosie said as she checked her tablet to confirm there was no outgoing connection.

‘Better gear up,’ Vern said, leading a charge into the garage and unlocking a hefty gun cabinet.

As Vern, Rosie and Harry pulled on body armour and grabbed automatic rifles, Ed yelled from out front.

‘There’s two cars coming, Harry!’ he called, as he came up the porch steps and into Vern and Rosie’s kitchen. ‘And my internet stopped working.’

Harry didn’t want to spook Ed, but it was hard not to, dressed in a flak vest and holding an assault rifle.

‘Is it zombies?’ Ed asked.

‘They’ll be at the gate in under a minute,’ Rosie said as she expertly loaded a clip into her assault rifle. ‘I’ll head upstairs and cover you boys.’

‘Ed, I need you to be calm and sensible, OK?’ Harry said.