“She has lately,” cried out old Fischer, “opened her father’s house to a cut-throat Socialist, who says openly he would steal anything from a richer man.  This is the end of it.  Here is the richer man—­and none the richer.”

“If you want the inside of my head you can have it,” said Brown rather wearily.  “What it’s worth you can say afterwards.  But the first thing I find in that disused pocket is this:  that men who mean to steal diamonds don’t talk Socialism.  They are more likely,” he added demurely, “to denounce it.”

Both the others shifted sharply and the priest went on: 

“You see, we know these people, more or less.  That Socialist would no more steal a diamond than a Pyramid.  We ought to look at once to the one man we don’t know.  The fellow acting the policeman —­Florian.  Where is he exactly at this minute, I wonder.”

The pantaloon sprang erect and strode out of the room.  An interlude ensued, during which the millionaire stared at the priest, and the priest at his breviary; then the pantaloon returned and said, with staccato gravity, “The policeman is still lying on the stage.  The curtain has gone up and down six times; he is still lying there.”

Father Brown dropped his book and stood staring with a look of blank mental ruin.  Very slowly a light began to creep in his grey eyes, and then he made the scarcely obvious answer.

“Please forgive me, colonel, but when did your wife die?”

“Wife!” replied the staring soldier, “she died this year two months.  Her brother James arrived just a week too late to see her.”

The little priest bounded like a rabbit shot.  “Come on!” he cried in quite unusual excitement.  “Come on!  We’ve got to go and look at that policeman!”

They rushed on to the now curtained stage, breaking rudely past the columbine and clown (who seemed whispering quite contentedly), and Father Brown bent over the prostrate comic policeman.

“Chloroform,” he said as he rose; “I only guessed it just now.”

There was a startled stillness, and then the colonel said slowly, “Please say seriously what all this means.”

Father Brown suddenly shouted with laughter, then stopped, and only struggled with it for instants during the rest of his speech.  “Gentlemen,” he gasped, “there’s not much time to talk.  I must run after the criminal.  But this great French actor who played the policeman—­this clever corpse the harlequin waltzed with and dandled and threw about—­he was—­” His voice again failed him, and he turned his back to run.

“He was?” called Fischer inquiringly.

“A real policeman,” said Father Brown, and ran away into the dark.