IT HAD BEEN agreed that it would be best for Irene to sit behind. She would be less conspicuous herself, and Kindell would have the appearance of driver rather than companion. He looked back over his shoulder to ask, "Can you describe the house, so that I can approach it without hesitation?"

"Yes. It is the second on the left of a row which have flights of steps in front, and porticos with white pillars. You'll see it easily."

"Steps? You think you'll manage alone?"

"I call that rude. If Father heard you, there'd be an international incident. What do you think American girls are?"

"What are they? Hydraulic cranes . . .? You promise you won't go in?"

"Well - not unless we agree I shall."

"How do you propose to consult me, while I'm in the car?"

"If they press me to go in to change the cases inside, I shall say, 'Very well, but I must tell my chauffeur to wait,' and I'll run back to you; and if things look fishy I'll hop in, and we'll drive away."

"Yes. That ought to - sit back, so that you can't be seen from the house. CFS4602. Can you remember that? Can you write it down? . . . I know this isn't the house. . . . Have you got that number? . . . Number 4602. . . . Yes, that's right. But it's most likely a fake."

"You're going to follow it?"

"I'm going to try. It isn't easy in London streets. Not without giving the game away. Particularly not in this car, if they know only half of what they probably do. But we'll do what we can.

The abrupt change in the tenor of this conversation had taken place as they had turned into the square, and Kindell had driven the car up to the pavement fifty yards before that at which he had been directed to stop. He had done this at the sight of a low grey car standing before Mrs. Collinson's gate, and a man descending her steps carrying what, by an easy guess, was the suitcase which Thurlow had stuffed with stone.

Kindell thought hard, as he followed the grey car into Mostyn Road. He said: "Listen, Irene. We've got to pull this off, or we shall be almost back where we were, and your father'll get most of the blame. Gustav's going to stick it out that I really did send the valise to you, more likely than not, and you can see where we shall be."

"We shall be through the windscreen more likely than not, if you keep driving like that."

"Sorry. It couldn't be helped. Got any money?"

"Yes. Three or four pounds. Why?"

"That ought to do. The next time I slow down at the traffic lights, I want you to slip out, so that they won't see you. Stop the first taxi you can, and follow me. Tell your driver to follow the grey car. As soon as I see you've taken up the chase, I shall turn off. I've got to get the police on the alert. That car can move, and even if we can't keep it in sight, I don't mean it to get away.

"But if you can keep on its track till it delivers the case, I want you to drop out then, get the nearest call-box, ring up Scotland Yard, ask for Mr. Allenby - you'll find you'll be put through at once - and report to him. Dell your driver to keep on following the car, and not to lose sight of it till it's gone to earth somewhere where it's clear that it's putting up. Give him plenty, and tell him there'll be five pounds more for............