Police headquarters presented an unusual air of preoccupation next morning.  In the corner office the telephone rang often and imperatively, several times erect figures in khaki and broad “Texas” hats flashed by the doorway, the drone of earnest conference sounded a few minutes, and the figures flashed as suddenly out again into the world.  In the inner office I glanced once more in review through the “Rules and Regulations.”  The Zone, too, was now familiar ground, and as for the third requirement for a policeman—­to know the Zone residents by sight—­a strange face brought me a start of surprise, unless it beamed above the garb that shouted “tourist.”  Now all I needed was a few hours of conference and explanation on the duties, rights, and privileges of policemen; and that of course would come as soon as leisure again settled down over headquarters.

Musing which I was suddenly startled to my feet by “the Captain” appearing in the doorway.

“Catch the next train to Balboa;” he said.  “You’ve got four minutes.  You’ll find Lieutenant Long on board.  Here are the people to look out for.”

He thrust into my hands a slip of paper, from another direction there was tossed at me a new brass-check and “First-Class Private” police badge No. 88, and I was racing down through Ancon.  In the meadow below the Tivoli I risked time to glance at the slip of paper.  On it were the names of an ex-president and two ministers of a frowsy little South American republic during whose rule a former president and his henchmen had been brutally murdered by a popular uprising in the very capital itself.

In the first-class coach I found Lieutenant Long, towering so far above all his surroundings as to have been easily recognized even had he not been in uniform.  Beside him sat Corporal Castillo of the “plain-clothes” squad, a young man of forty, with a high forehead, a stubby black mustache, and a chin that was decisive without being aggressive.

“Now here’s the Captain’s idea,” explained the Lieutenant, as the train swung away around Ancon hill, “We’ll have to take turns mounting guard over them, of course.  I’ll have to talk Spanish, and nobody’d have to look at Castillo more than once to know he was born up in some crack in the Andes.”—­Which was one of the Lieutenant’s jokes, for the Corporal, though a Colombian, was as white, sharp-witted, and energetic as any American on the Zone.  —­“But no one to look at him would suspect that Fr—­French, is it?”

“Franck.”

“Oh, yes, that Franck could speak Spanish.  We ’ll do our best to inflate that impression, and when it comes your turn at guard-mount you can probably let several little things of interest drift in at your ears.”

“I left headquarters before the Captain had time to explain,” I suggested.