It was seven o'clock before Alex finally got back to the flat. Chicago had decided to hit the town, and the streets were full of people. Alex dodged between them with the man's backpack over his shoulder. He found it hard to believe that everything was so ordinary, when a ruthless ancient criminal organization was orperating behind these people's backs, just waiting to wipe the CIA out. When he got in, Tamara made him a cup of tea before he explained.

"Oh, Alex. That was dangerous," she said, after he had finished the story. Alex didn't reply, instead taking out the backpack he had taken. He poured the contents out onto the table.

There was a floppy disk and a clear plastic folder containing some paper. Alex pulled the cover off the folder and pulled out the paper. It was a series of emails. He pulled out the first and began to read:

5/5/05

Inkheart,

Have successfully taken the role of Joe Brace and sent the encrypted emails. The CIA decrypted them and know about the leakage. Luckily, they can't decrypt this message, no matter how hard they try. The Chimera virus was in place at 0800 hours, but the files were scrambled.

Joe Brace

7/5/05

Inkheart,

The virus has successfully infiltrated the inner mainframe. All I need now is your word. Kelly arrived earlier and delivered the final software, but there were bugs for it. It looks like Brace only managed to develop three of the four parts.

Joe Brace

10/5/05

Inkheart,

CIA have been thrown into disarray, and they don't know what to do. Kelly is working on the last piece of the puzzle and the final copy has been updated.

Joe Brace

15/5/05

Inkheart,

Kelly has delivered the final software. The virus is in position and ready to be detonated. Some new people arrived at my flat today, they will have to be checked a woman and a boy, though of course it is too late. We can't be stopped, though CIA have appealed to MI6 for help on the 12/5/05. We are to be on our guard.

Alex finished reading and looked at Tamara.

"What does it mean?" she said. Alex didn't answer, but pulled out the laptop Smithers had given him. He booted it up and clicked on the Internet icon.

Lloyd wasn't impressed. A few months ago, he had let himself be bested by a kid. Alex Rider. He ground a pen into a piece of paper in frustration. It was because of that kid he was now on desk duty, staring at the two screens waiting for agents to get in touch. Rider had slipped past him and nearly assassinated his boss. Highly embarrassing, the kid should be rotting in prison, but he was too valuable. One of the screens suddenly lit up.

"Finally!" Lloyd said leaning forward. Then he snapped back as if he had just been hit into the face.

"You!"

"Yes," Alex said. "Me. What's a chimera?"

"A Greek monster," Lloyd said. He was a bit of an expert on myths and legends. Alex frowned, and Lloyd lent back.

"OK, OK," he said, typing it into the database. He consulted the screen. "Too many hits," he said. "Anything more specific?"

"Try Chimera virus," Alex said. Lloyd typed it in. Then paled.

"Chimera virus?" he said. "You . . . you haven't got one on your hands, have you?"

It was bad news. Lloyd had bought in Mrs Jones. She too, looked slightly disturbed.

"Alex," she said. "Listen. The Chimera virus was developed by Inkheart during their war against the CIA. When inserted into a computer database, it rampages around corrupting everything very, very quietly. Once a file is infected, it stays that way. The Chimera leaks the file which can be remote controlled to be sent to a location via email. The Chimera then deletes the file. It nearly let Inkheart win the war. Inkheart could know when the CIA would attack and where."

"It sounds like the perfect weapon to me," Alex said. "Why didn't Inkheart win, then?"

"Chimera seems like the perfect weapon," Mrs Jones continued after throwing another peppermint into her mouth. "But, there was a flaw in the programming. Chimera couldn't be set off; it required more software to be developed. Chimera infected nearly every file in the CIA database but none of the files could be deleted or sent. Inkheart had made their mistake by launching themselves against the CIA too early. Their killer weapon couldn't work; it needed more time. So Joe Brace went straight into action. He argued with the CIA to attack Inkheart now, or the virus would go online and the CIA's every move would be in the hands of Inkheart. Brace got permission from the President and had a huge team of CIA and FBI agents sent out to discover the location of the leaders of Inkheart."

Alex frowned. "Why wasn't I told this before?"

Mrs Jones avoided his eyes, and paused.

"It, er, didn't seem relevant at the time, Alex."

"That's not true," Alex shouted. "You knew, but you just didn't want to make it sound dangerous!"

"Alex, look . . . "

"Forget it! I don't have to put up with this! Leave me alone!"

Mrs Jones sucked her Peppermint.

"Alex, we don't have time. You have to help Tamara before we go into a world wide crises."

Tamara and Alex stood on top of the staircase, staring at the door to Brace's apartment. Mrs Jones was sure the answers to their questions would be in there. The objectives: find out what you can and find and sabotage the Chimera virus. Before they had gone, she reminded them that this was an American mission, and Alex would have to obey Tamara's instructions if at all possible. Alex knew that Mrs Jones had made it sound easy, but it still seemed as if he were on the border of World War III.

The door opened. Tamara and Alex ducked out of sight. The man descended the staircase. Tamara took a deep breath, then pulled out an ordinary camera. She took five pictures of the man going down the stairs, then pulled back. She peered at the screen on the back of the camera. Alex looked over her shoulder. He knew that the CIA also carried gadgets, Tamara's shoelaces having saved Washington a month ago. A second later, the camera beeped and a name flashed on the top: Joe Brace.

"It's him," Tamara muttered. They took the stairs three at a time before jumping down onto the landing and rushing to the door. Alex pulled out the SNAG tool and the door was open in seconds.

"Neat," Tamara muttered as they rushed inside.

The flat was larger than theirs. Alex and Tamara split up, searching the rooms. The living room contained nothing, and nor did the bathroom or the kitchen. However, they got lucky in the study. An apple computer was standing on a large oak desk. Tamara booted it up and switched on the desk light, for it was getting dark.

"I'll check this out," she said. "Search the other rooms."

"For what?"

"Bags, disks, folders, anything," she replied distractedly. Alex ran out. Tamara held her breath. If the computer was password protected, then they would have to wait for a special force team to break into it. And if it alerted Inkheart, they might detonate a back-up copy of the virus into the CIA database. The computer beeped; she was in! Tamara breathed, and double clicked on My Documents. There was a folder labeled Chimera.

Alex was in the bedroom. He rummaged through some drawers, then checked under the bed. He pulled out a thin canvas bag, then pulled it open. Inside, there was a floppy disk and some other items. There was a large set of CDs and a folder. He pulled it out, and examined the wad of paper inside. What he saw made his stomach contract.

Tamara opened several of the Chimera documents at once. The first seemed to be a diary of events. Tamara read through the last five:

Have successfully transferred the latest research and updated the detonation software.

Another flaw developed today, must be wrapped.

Isolated flaw and corrected it. New software transferred today. Inkheart sent new research.

Research used to update software. Tested it, close to perfect but some of the virus failed to detonate.

Corrected flaws, all viruses detonated. Only remaining flaw is a Chute flaw. Inkheart will correct it. Sent final software off today to HQ.

Tamara couldn't believe what she was reading. The diary told exactly Brace's road of treachery. He had been developing the Chimera, for about two weeks. And he had sent a copy of the detonation software to Inkheart. It was too late. She checked the other documents. Most were saved emails from Inkheart, informing Brace how to create the detonation software. Brace had betrayed them. But even as she thought it, Tamara knew it wasn't true. Brace wouldn't have betrayed them to Inkheart. It didn't make any sense. Brace had bought Inkheart to its knees and killed the Chimera. Now he was working for Inkheart? Tamara heard Alex step into the room. She looked at the last file in the chimera folder. It was the detonation software. She looked behind her and saw Alex. But he wasn't alone. Three men were with him, Brace and two others. One was gaunt and white, and looked as if he had recently suffered a great deal of pain. There was a bruise on his face, and he was looking at Alex with intense dislike. He was wearing a black coat. Tamara stood up, and lifted her hands.