The door swung sharply outward.

There came a blinding flash, and with it the dense smoke of some pungent, gas-reeking chemical. Eyes smarted and watered. Staggering back from the surprise attack, totally unexpected, Don, Garry and Chick took an instant to cower back against the wall, shielding their faces.

There was the play of a flashlamp about the room.

Then, before either of them could recover from astonishment and from the choking smudge enough to move, there came the clank of some metal, and the slam of the door.

“Oh!” Chick gasped, and then said no more, choking in the smoke of the bomb or whatever poured its dense, stifling smoke up, filling the small, almost airtight compartment.

It took Garry, nearest the door, half a minute of choked, almost suffocated effort, fumbling in the dark, to get the handle of the door and twist it. The door was not locked; but, as he dragged Chick out and Don leaped over the fuming, pungent smoke-flare that had been ignited and dropped in the dark room, Garry saw that the rubber catch-all mat on the floor was burning.

The designing room, with its unreplaceable, valuable files, was adjacent to the dark room. Below, in the workshops, “dope” and other dreadfully inflammable materials lay stored. In the hangar next it were airplanes worth thousands of dollars, including a fourteen-ton, double-bodied seaplane that had been ordered by the Mexican Government.

“One go one way, the other to the bank stairway—or the fire escape!” he screamed to Don and Chick.

Himself, ignoring the lost film—knowing well that was what had vanished in the hands of their adversary—Garry raced for a fire extinguisher.

Choked, blinded, staggering, Don and Chick heard, but had difficulty getting their bearings.