Of the fate of the secret agent and his fighting attendant, however, no tidings came up from the mottled plain.
Somebody might know in the clean, white lodge-keeper’s kitchen, where the canary sang, but there was no available excuse to turn downward the swiftly sailing biplanes when they swept over the one bright spot in all that forbidding surface.
“I can recommend your license as master pilots,” jovially observed one of the officers when the machines again rested in the aviation field, just at sunset.
The other observer nodded approval of the compliment to the youngsters, and both found it not beneath their dignity to give Billy and Henri a hearty handshake.
The young aviators had hardly completed the housing of the biplanes when they were accosted by a loutish lad attired in a smock-frock and leather leggins.
With a pull at his forelock, the boy handed Billy a fold of notepaper, and then shuffled away.
“Some more shady business,” muttered Billy, opening the message.
One line, that was all:
“To-morrow noon. Sign of thumb.”
“Why can’t that fellow let us alone?”