n a chance of losing his man.

"He's turning south on Fenchurch," Houston said a little later. "I
wonder where he's going."

"Keep after him," said Headquarters. "Our net men haven't spotted either
of you yet. They can hardly see across the street in this damned fog."

Houston kept going.

"What the hell?" he whispered a few minutes later. "He's still following
Fenchurch Street! He's doubling back!"

Leadenhall Street, the banking center of the City of London, runs almost
due east-and-west; Fenchurch Street makes a forty-five degree angle with
it at the western end, running southwest for a bit and then curving
toward the west, toward Lombard.

"Houston," said HQ, "touch your left ear."

Houston obediently reached up and scratched his left ear.

"Okay," said HQ. "Bogart's spotted you, but he hasn't spotted Sir Lewis.
Bogart's across the street."

"He can't miss Sir Lewis," whispered Houston. "Conservatively
dressed--matching coat and trousers of orange nylon tweed--royal blue
half-brim bowler--carrying a blue brief case."

There was a pause, then: "Yeah. Bogart's spotted him, and so has
MacGruder. Mac's on your side, a few yards ahead."

"Check. How about the rest of the net?"

"Coming, coming. Be patient, old man."

"I _am_ patient," growled Houston. _I have to be_, he thought to
himself, _otherwise I'd never stay alive_.

"We've got him bracketed now," HQ said. "If we lose him now, he's a
magician."

Sir Lewis walked on, seemingly oblivious to the group of men who had
surrounded him. He came to the end of Fenchurch Street and looked to his
left, towards London Bridge. Then he glanced to his right.

"I think he's looking for a cab," Houston whispered.

"That's what MacGruder says," came the reply. "We've got Arthmore in a
cab behind you; he'll pick you up. MacGruder will get another cab, and
we have a private car for Bogart."

Sir Lewis flagged a cab, climbed in, and gave an address to the driver.
Houston didn't hear it, but MacGruder, a heavy-set, short, balding man,
was standing near enough to get the instructions Sir Lewis had given to
the driver.

* * * * *

A cab pulled up to the curb near Houston, and he got in.

Arthmore, the driver, was a thin, tall, hawknosed individual who could
have played Sherlock Holmes on TV. Once he got into character for a
part, he never got out of it unless absolutely necessary. Right now, he
was a Cockney cab-driver, and he woul