After 10 years, Liz Carlyle was still the feistiest, quirkiest and most understatedly attractive MI5 operative on the block. Bruno Mackay from MI6 was holding forth in the briefing room. There was something about him she didn't trust: he looked like David Shayler.

"Our team in Pakistan tell us that Faraj Mansoor, an al-Qaida operative, is on his way to Britain," he was saying. "We also hear he will be working with an invisible."

"An invisible is someone who could pass as English without arousing comment," Liz said out loud for no reason other than to fill the reader in. She checked her emails. There was a message from her agent Marzipan; something strange was happening in Norfolk. Could this be the crucial break?

"I had to kill a man at the pick-up," said Faraj. Lucy's blood ran cold. She had been ready for this since she had changed her old, posh name at the Afghan training camp. "It's time to go to the toy shop and the chemist to buy the ingredients for the C4 explosive," she announced in a clumsy sentence, designed to keep the plot moving.

Liz was closing in. The 7.62mm bullet could only have been used by a terrorist, and the Astra on the CCTV had been traced to a rental agency at Waterloo. The driver must be the invisible.

"Check all British women passengers who arrived on the Eurostar," she barked.

"No joy," said her No 2.

The invisible had to be on the list. Liz cross-checked the names. Jean D'Aubigny. "We thought he was a Frenchman, but she's a posh woman," she shouted, without any shame at such an obvious contrivance. "Now we have to work out why she's here."

Faraj and Jean killed another two people before moving silently through the fens.

"When will you tell me the target?" Jean asked.

"When it's time."

"We must hurry. We are being pursued by a woman and she is getting near."

"Truly you are telepathic."

Bruno and Liz checked out the USAF bases. There was something about the connection between Bruno and the Marwell commander that rang false.

"It's time," said Faraj. "The Americans in Marwell killed my fiancee by bombing an Afghan wedding party. At school you were best friends with the base commander's daughter and know the house well."

"You've been holding out on me about about the wedding party," Liz snapped at Bruno, "and Jean knew the base commander's daughter. That's the target."

"Well done, Liz," said her boss, as she recovered in hospital after the blast. "Thanks to you both the terrorists are dead. By the way, Bruno never told us Faraj had been an MI6 agent before the wedding bomb. Keep it up and you'll run MI5 one day."

The digested read ... digested

The former Queen of Spooks lets her imagination get the better of her as she relives her fantasies.