It has been an eventful day for many, no doubt; of its events for our hero, Frank Mansfield, his mother restored to reason and the world, and his faithful friends, the "Bats in the Wall," we have no time to speak. Meanwhile, the virtuous Mr. Callister appeared at his office as usual, and figured prominently in several large transactions on the floor of the Stock Exchange. The new clerk, Mr. Maxwell, however, did not appear at the office, nor had Detective Hook been seen by any one. The police authorities, now thoroughly alarmed by his continued absence, caused a general alarm to be sent out, and during the entire day his brother detectives searched for him in all directions, but in vain. Now, upon the night of the day in question, had any one chanced to stand upon the bulkhead of the East river front at a point somewhere between Catherine street and the Market slip, they might have observed a man of most singular appearance creep apparently out of the solid wall of the bulkhead itself, and, with evident effort, leap to the deck of a little sloop lying within arm's-length of the street line. Once upon the deck of the sloop, he did not pause, but seizing the string-piece of the bulkhead, drew himself to the ground above, and standing erect, gave vent to a sigh of relief. And no wonder. From head to foot he was a mass of dripping mud. "Safe--safe at last!" he muttered; "safe and free to act once more. It still lacks something of twelve--if my strength holds out I may make it yet. I will make it. Let Elijah Callister beware, for the day of his reckoning at last has come." Turning abruptly he crossed South street and disappeared in the dark shadows of the great warehouses which cluster around the East river shore. Who is this man who swears vengeance upon so worthy, so pious a member of society as Mr. Elijah Callister of the Tenth Baptist Church? His name is Caleb Hook. His business is that of a police detective. Reuben Tisdale was right. Out of the whale's belly the avenger has come. Fate had indeed willed that he should prove the Jonah of the band. * * * * * "Now, then, Billy, you slip up the steps and try the door. If the watchman has not gone back on us, it ought to open at the first touch." Before the Lispenard Bank stood three men, well disguised in great coats and low slouch hats, one carrying a small grip-sack in his hand. They are Elijah Callister and the two Cutts--father and son. It is the stock broker who speaks, and Billy Cutts, the renegade detective, is the one who creeps up the steps of the Lispenard Bank in obedience to his command. "Is it all right, Billy?" whispered Cutts, the elder. "We want to get off the street as soon as we possibly can." "All right, dad, come on." The two men moved stealthily toward the steps of the bank. "Squeak! squeak! squeak!" Behind them a low, bat-like cry went up for one instant only, and then all was still.