He caught up with her in the cattle chute that herded passengers into the arrivals hall. A low-level operative from London Station was standing along the railing, next to a pair of black-veiled women. He was holding a paper sign that read ashton and wearing an expression of profound boredom. He jammed the sign into his pocket and fell in next to Gabriel as he threaded his way through a tearful family reunion.

“Where’s the car?”

The operative nodded toward the left-most door.

“Go back to the rail and hold up your sign. Another man will be along in a few minutes.”

The operative dropped away. Outside, a line of taxis and airport shuttles waited in the early-afternoon gloom. The woman threaded her way through the traffic and headed for the short-stay car park. It was the one scenario for which Gabriel had not accounted. He drew his BlackBerry and called Keller.

“Where are you?”

“Passport control.”

“There’s a man in the arrivals hall holding a sign that says Ashton. Tell him to take you to the car.”

Gabriel rang off without another word and followed the woman into the car park. Her vehicle was on the second level, a blue BMW sedan, British registration. She fished the key from her handbag, popped the locks with the remote, and lowered herself into the driver’s seat. Gabriel rang Keller a second time.

“Where are you now?”

“Behind the wheel of a silver Passat.”

“Meet me at the exit of short-term parking.”

“Easier said than done.”

“If you’re not there in two minutes, we’re going to lose her.”

Gabriel killed the call and concealed himself behind a concrete pillar as the BMW passed. Then he headed down the ramp at a trot and returned to the arrivals level of the terminal. The BMW was nosing from the exit. It slid past Gabriel’s position and disappeared from sight. Gabriel started to dial Keller a third time but stopped when he saw the flashing headlamps of a rapidly approaching Volkswagen. He swung into the passenger seat and waved Keller forward. They caught up with the BMW as it was turning onto the A4, bound for West London. Keller eased off the throttle and lit a cigarette. Gabriel lowered his window and rang Graham Seymour.

The call arrived during a brief lull between a meeting of his senior staff and a visit by the chief of Jordanian intelligence, a man whom Seymour secretly loathed. Seymour jotted down the key details. Later, he wished he had not. A woman named Anna Huber, German passport, Frankfurt address, had just arrived in London via Lisbon, where she had passed a single night in an apartment connected to Eamon Quinn. At Heathrow Airport she had collected a blue BMW, British registration AG62 VDR, from the short-stay car park. The car was now headed toward London, followed by the future chief of Israeli intelligence and an SAS deserter turned professional assassin.