While the Clock Ticked

I A MYSTERIOUS TIP II PUZZLING CLUES III GRIM WARNING IV STORMY SLEUTHING V STOLEN TREASURE VI WATERFRONT CHASE VII CRAFTY THIEVES VIII A PERILOUS PLUNGE IX THE SECRET ROOM X THE SHADOWY FIGURES XI A SUSPICIOUS CAPTAIN XII METEOR SPECIAL XIII THE EAVESDROPPER XIV SUDDEN ATTACK XV THE VANISHING CAR XVI A MISSING CLIENT XVII A DANGEROUS TICKING XVIII THE SLIPPERY ROOFTOP XIX A NARROW ESCAPE XX HIDDEN LOOT