Then it stopped.

‘What the hell is going on?’ Garcia asked, lifting his palms up.

Hunter shook his head. His full attention never leaving the screen.

The camera zoomed out just a little, and all of a sudden the submerged portion of the pipes sprang back into life. Like a Jacuzzi bath, the underwater jets ruffled the water as they spat more liquid into the enclosure. But there was something different this time. As the colorless liquid exited the pipes and mixed with the water, it was producing an odd effect, as if the new liquid was denser than that already inside the enclosure.

Hunter leaned forward, bringing his face closer to the monitor.

‘That’s not water,’ he said.

‘What?’ Garcia asked, standing right behind him. ‘What do you mean?’

‘Different density,’ Hunter replied, pointing at his screen. ‘Whatever he’s pumping into that tank, it isn’t water this time.’

‘What the hell is it, then?’

At that moment something started flashing at the top right-hand corner of the picture. Four letters inside parentheses. The first, third and fourth were in capitals.

(NaOH)

‘Is that a chemical formula?’ Garcia pointed to it.

‘Yes.’ Hunter breathed out.

‘For what?’ Garcia rushed back to his computer and opened a new tab on his web browser.

‘No need to search for it, Carlos,’ Hunter said grimly. ‘That’s the chemical formula for sodium hydroxide . . . caustic soda.’

Seven

Garcia felt a knot tighten in his throat. Years ago, when he was still just a uniformed LAPD cop, he’d responded to a domestic violence incident where a jealous boyfriend had thrown half a pint of caustic soda in his girlfriend’s face. The boyfriend fled the scene but was arrested five days later. Garcia still remembered helping the paramedics strap the girlfriend down to the gurney. Her face was just a mess of raw flesh and burned skin. Her lips looked like they had melted onto her teeth. Her right ear and nose had totally disintegrated, and the solution burned holes into one of her eyeballs.

Garcia looked at Hunter over his computer. ‘No way. Are you sure?’

Hunter nodded. ‘I’m sure.’

‘Sonofabitch.’

The phone on Hunter’s desk rang again. It was Dennis Baxter from the Computer Crimes Unit.

‘Detective,’ he said in an anxious voice. ‘NaOH is caustic soda. Sodium hydroxide.’

‘Yes, I know.’

‘Shit, man. That stuff is highly corrosive. Many times worse than acid. If somebody is dumping sodium hydroxide into that much water, for now, the solution will be over-diluted and not very strong, but soon . . .’ He went silent.

‘It will turn that whole thing into an alkaline bath,’ Hunter finished the sentence Baxter couldn’t.

‘That’s right. And you know what that will do?’

‘Yes, I know.’

‘Holy shit, Detective. What’s going on?’

‘I’m not sure. Did you manage to trace the transmission?’

‘Yes. It’s coming from Taiwan.’

‘What?’

‘Exactly. Whoever is doing this . . . he’s good. It’s either a hijacked IP address or he stole one from a Taiwanese server pool. Bottom line . . . We can’t trace it.’

Hunter put the phone down. ‘We can’t get him through the Internet transmission either,’ he told Garcia.

‘Shit. This is messed up, man.’

The man on the screen started shaking again. But this time Hunter could tell it wasn’t from fear or cold. It was excruciating pain. The solution was getting stronger and starting to corrode his skin. His mouth opened wide to release an agonizing scream that neither Hunter nor Garcia could hear. Secretly, both detectives were relieved by the lack of sound.

As more and more caustic soda was added to the mixture, the water started gaining a faint, dull, milky color.

The man closed his eyes and started shaking his head violently from side to side, as if having a seizure. The alkaline bath was starting to scrape away his skin like an electric sander. It took only a few seconds for the first pieces of skin to be ripped from his body.

Hunter rubbed his face with both hands. He had never felt so helpless.

As more and more skin started to float around the tank, the water began to change color again. It was now going pink. His entire body was bleeding.

The camera zoomed in on something else floating inside the enclosure.

‘What is that?’ Garcia asked, pulling a face.

Hunter pinched his bottom lip. ‘It’s a fingernail. His body is dissolving.’

The camera zoomed in on another one, and another one. The solution had already dissolved his cuticles and most of the nail beds on his fingers and toes.

The water was getting bloodier. They couldn’t see through it anymore. The man’s face, though, was still above the water line.

The victim had lost control of his body, which was now shaking incessantly, guided only by pain. His eyes had rolled back into his head. His mouth was contorted into an excruciating shape. His teeth were relentlessly grinding against each other, and he was now bleeding from the gums, nose and ears as well.

The water was starting to boil.

The man convulsed for the last time. His chest kicked forward so violently it looked like there was something inside it, trying to explode out of his body. His chin fell to his chest, submerging his face under the bloody water and sodium hydroxide mixture.

There was no more movement.

The camera zoomed out, showing the entire glass enclosure.

Hunter and Garcia couldn’t find any words. They couldn’t look away either.

A few seconds later a message flashed across their screens.

I HOPE YOU’VE ENJOYED THE SHOW.

Eight

The LAPD’s Robbery Homicide Division’s captain, Barbara Blake, wasn’t easily intimidated and, after so many years in the force, very little ever shocked her, but this morning she sat in absolute silence inside her office on the fifth floor of the Police Administration Building with a disbelieving look on her face. The office was spacious enough. The south wall was taken by bookshelves crammed with hardcovers. The north one by framed photographs, commendations and achievement awards. The east wall was a floor-to-ceiling panoramic window, looking out over South Main Street. Directly in front of her desk were two comfortable-looking leather armchairs, but none of the three other people inside her office were occupying them.

Hunter, Garcia and Dennis Baxter were all standing behind Captain Blake’s desk, staring at her computer monitor, watching the footage Baxter had captured from the Internet minutes earlier. The Operations Office had also already sent Hunter a copy of the recorded telephone conversation between him and the mysterious caller.

Captain Blake listened to the recording and watched the entire footage without uttering a word. At the end of it all she looked up at Hunter and Garcia, her face paler than moments ago.

‘Was this real?’

Her stare jumped to Baxter, who was a big man, none of it muscle. He was in his forties, with curly fair hair, a plump face made heavier by a double chin, and a thin mustache that looked more like peach fuzz.

‘I mean,’ she said. ‘I know that nowadays CGI technology can make anything look real. Can we be sure that this whole thing isn’t just digital and camera trickery?’

Baxter shrugged.

‘Well, you’re the head of the Computer Crimes Unit.’ The captain’s voice went hard. ‘Tell me something.’