will see a man sitting alone at a table.  He will have a red flower on his coat.  You are to say, “A fine opera is ‘I Pagliacci.’” If he answers, “Not without Gennaro,” lay the newspaper down on the table.  He will pick it up, leaving his own, the Bolletino.  On the third page you will find written the place where your daughter has been left waiting for you.  Go immediately and get her.  But, by the God, if you have so much as a shadow of the police near Enrico’s your daughter will be sent to you in a box that night.  Do not fear to come.  We pledge our word to deal fairly if you deal fairly.  This is a last warning.  Lest you shall forget we will show one other sign of our power to-morrow.

LA MANO NERA.

* * * * *

The end of this ominous letter was gruesomely decorated with a skull and cross-bones, a rough drawing of a dagger thrust through a bleeding heart, a coffin, and, under all, a huge black hand.  There was no doubt about the type of letter that it was.  It was such as have of late years become increasingly common in all our large cities, baffling the best detectives.

“You have not showed this to the police, I presume?” asked Kennedy.

“Naturally not.”

“Are you going Saturday night?”

“I am afraid to go and afraid to stay away,” was the reply, and the voice of the fifty-thousand-dollars-a-season tenor was as human as that of a five-dollar-a-week father, for at bottom all men, high or low, are one.

“‘We will not fail as we did Wednesday,’” reread Craig.  “What does that mean?”

Gennaro fumbled in his pocketbook again, and at last drew forth a typewritten letter bearing the letter-head of the Leslie Laboratories, Incorporated.

“After I received the first threat,” explained Gennaro, “my wife and I went from our apartments at the hotel to her father’s, the banker Cesare, you know, who lives on Fifth Avenue.  I gave the letter to the Italian Squad of the police.  The next morning my father-in-law’s butler noticed something peculiar about the milk.  He barely touched some of it to his tongue, and he has been violently ill ever since.  I at once sent the milk to the laboratory of my friend Doctor Leslie to have it analyzed.  This letter shows what the household escaped.”

“My dear Gennaro,” read Kennedy.  “The milk submitted to us for examination on the 10th inst. has been carefully analyzed, and I beg to hand you herewith the result: 

  “Specific gravity 1.036 at 15 degrees Cent.

Water       84.60 per cent. 
Casein       3.49   "   "
Albumin     56      "   "
Globulin     1.32   "   "
Lactose      5.08   "   "
Ash         72      "   "
Fat          3.42   "   "
Ricin        1.19   "   "

“Ricin is a new and little-known poison derived from the shell of the castor-oil bean.  Professor Ehrlich states that one gram of the pure poison will kill 1,500,000 guinea pigs.  Ricin was lately isolated by Professor Robert, of Rostock, but is seldom found except in an impure state, though still very deadly.  It surpasses strychnin, prussic acid, and other commonly known drugs.  I congratulate you and yours on escaping and shall of course respect your wishes absolutely regarding keeping secret this attempt on your life.  Believe me,