“Sure thing,” said Pennell.  “But come on; we’ll miss them.”

They set out after the girls, who, after one glance back, walked on as if they did not know they were being followed.  But they walked slowly, and it was easy for the two men to catch them up.

Peter slackened a few paces behind.  “Look here, Pen,” he said, “what the deuce are we going to do?  They’ll expect more than a drink, you know.”

“Oh no, they won’t, not so early as this.  It’s all in the way of business to them, too.  Let’s pass them first,” he suggested, “and then slacken down and wait for them to speak.”

Peter acquiesced, feeling rather more than an ass, but the drinks had gone slightly to his head.  They executed their share of the maneuver, Pennell looking at the girls and smiling as he did so.  But the two quickened their pace and passed the officers without a word.

“If you ask me, this is damned silly,” said Peter.  “Let’s chuck it.”

“No, no; wait a bit,” said Pennell excitedly.  “You’ll see what they’ll do.  It’s really an amusing study in human nature.  Look!  I told you so.  They live there.”

The girls had crossed the street, and were entering a house.  One of them unlocked the door, and they both disappeared.  “There,” said Peter, “that finishes it.  We’ve lost them.”

“Have we?” said his companion.  “Come on over.”

They crossed the street and walked up to the door.  It was open and perhaps a foot ajar.  Pennell pushed it wide and walked in.  “Come on,” he said again.  Peter followed reluctantly, but curious.  He was seeing a new side of life, he thought grimly.

Before them a flight of stairs led straight up to a landing, but there was no sign of the girls.  “What’s next?” demanded Peter.  “We’ll be fired out in two twos if nothing worse happens.  Suppose they’re decent girls after all; what would you say?”

“I’d ask if Mlle. Lucienne lived here,” said Pennell, “and apologise profusely when I found she didn’t.  But you can’t make a mistake in this street, Graham.  I’m going up.  It’s the obvious thing, and probably what they wanted.  Coming?”

He set off to mount the stairs, and Peter, reassured, followed him, at a few paces.  When he reached the top, Pennell was already entering an open door.

“How do you do, ma cherie?” said one of the girls, smiling, and holding out a hand.

Peter looked round curiously.  The room was fairly decently furnished in a foreign middle-class fashion, half bedroom, half sitting-room.  One of the girls sat on the arm of a big chair, the other was greeting his friend.  She was the one he had fancied, but a quick glance attracted Peter to the other and elder.  He was in for it now, and he was determined to play up.  He crossed the floor, and smiled down at the girl on the arm of the chair.

“So you ’ave come,” she said in broken English.  “I told Lucienne that you would not.”