otland Yard where I
was interviewed by a detective-inspector to whom I revealed the
hiding-place of the much-wanted criminal.

He thanked me, and then began to inquire what I knew concerning him.
In return, I told him of my friendship with the great Spanish
detective Rivero, and how, with the latter, I had seen Sanz at the
station at Montauban.

Presently he rose, and telling me he would search for any request from
the Spanish Government for the man's arrest, he left me.

He returned a quarter of an hour later with some papers in his hands,
and said:

"I find that the Madrid police have applied to us for this
individual's arrest, and here is his photograph," and he showed me one
similar to that which Rivero had sent me to Amsterdam.

I, of course, made no mention of Oswald De Gex, but it suddenly
occurred to me that if Sanz were arrested De Gex might take fright, so
I suggested that the Spaniard be kept under surveillance until the
Spanish police were communicated with.

"I believe Senor Rivero suspects that Sanz is one of a very dangerous
gang," I said. "If so, it would be well to arrest them all."

"Are the others in London, do you think?" asked the tall, dark-haired
official of the Criminal Investigation Department.

"Ah! That I do not know," was my reply. "I only know that Mateo Sanz
is a very dangerous person, who has been wanted for several years."

"Well, we thank you very much for your information, sir, and we shall
act upon it at once," he replied. And then I went along the stone
corridor and out again into Parliament Street, well satisfied that I
had, at last, placed one of the criminals in the hands of the police,
who would, in due course, learn the true facts concerning Baron van
Veltrup's mysterious end.

CHAPTER THE TWENTY-SEVENTH

A CURIOUS STORY

At Scotland Yard they acted upon my suggestion, and at once sent a
wireless message to Senor Rivero in Madrid, telling him of the
discovery of the notorious Mateo Sanz.

In the meantime my curiosity was further aroused by a note sent to me
by Mrs. Tennison's servant, Mrs. Alford, next day, saying that Doctor
Moroni had called at Longridge Road and that, finding Miss Gabrielle
absent, he had put to her a number of questions concerning myself.

"As I promised you, sir," the woman wrote, "I pleaded ignorance of
everything. He was apparently astonished to find my mistress and Miss
Gabrielle away. He asked me for their address, but I replied