"When?" demanded Selwood.

"Tonight!" replied Mrs. Engledew. "Tonight--at an hour to be fixed after
your agreement to their terms."

Selwood felt himself in a difficult position. Mr. Tertius was out of
town for the day, gone to visit an antiquarian friend in Berkshire: Mr.
Halfpenny lived away down amongst the Surrey hills. Still, there was
Cox-Raythwaite to turn to. But it seemed as if the lady desired an
immediate answer.

"You know these men?" he asked.

"One only, who represents both," answered Mrs. Engledew.

"Why not point him out to the police, and let them deal with them?"
suggested Selwood. "They would get his evidence out of him without any
question of price!"

"I have given my word," said Mrs. Engledew. "I--the fact is, I am mixed
up in this, quite innocently, of course. And I am sure that no living
person knows the truth except these men, and just as sure that they will
not tell what they know unless they are paid. The police could not make
them speak if they didn't want to speak. They know very well that they
have got the whip-hand of all of us in that respect!"

"Of you, too?" asked Selwood.

"Of me, too!" she answered. "Nobody in the world, I'm sure, knows the
secret but these men. And it's important to me personally that they
should reveal it. In fact, though I'm not rich, I'll join Miss Wynne in
paying their price, so far as a thousand pounds is concerned. I would
pay more, but I really haven't got the money--I daren't go beyond a
thousand."

Selwood felt himself impressed by this candid offer.

"Precisely what do they ask--what do they propose?" he asked.

"This. If you agree to pay them ten thousand pounds, you and Professor
Cox-Raythwaite are to meet them tonight. They will then tell the true
story, and they will further take you and the police to the man, the
real murderer," answered Mrs. Engledew. "It is important that all this
should be done tonight."

"Where is this meeting to take place?" demanded Selwood.

"It can take place at my flat: in fact, it must, because, as I say, I am
unfortunately mixed up," said Mrs. Engledew. "If you agree to the terms,
you are to telephone to me--I have written my number on the card--at two
o'clock this afternoon. Then I shall telephone the time of meeting
tonight, and you must bring the money with you."

"Ten thousand pounds in cash--on Sunday!" exclaimed Selwood. "That, of
course, is utterly impossible."

"Not cash in that sense," replied Mr