Chapter

I—THE BOY FLIERS

II—ON GUARD

III—NOT CAUGHT NAPPING

IV—THE STARTLING NEWS

V—THE EXCITEMENT GROWS

VI—FIGURING IT ALL OUT

VII—THE AIR SCOUTS

VIII—JUST BELOW THE CLOUDS

IX—THE PILOT OF THE MERMAID

X—HEARD OVER THE WIRE

XI—COMPARING NOTES

XII—AT THE HOSKINS FARM

XIII—THE BUTTERFLY COLLECTOR

XIV—A CLUE

XV—WHEN CASPER CAME BACK

XVI—THROWING OFF THE MASK

XVII—SALLIE RIDES BAREBACK

XVIII—AN AEROPLANE CHASE

XIX—DROPPING A "BOMB!"

XX—OVER LAND AND SEA

XXI—OVER THE BOUNDARY LINE

XXII—THE HYDROPLANE RESCUE

XXIII—BROUGHT TO BOOK—CONCLUSION