"Whoom!"
The sound of the bursting bomb was nearer.
"'Tis safer in the air," said Tam as he swung into his fuselage. "Contact!"
A few seconds later, with a roar, the machine disappeared into the black wall of darkness.
It came back in less than a minute well overhead and Blackie, straining his eyes upward, followed its progress against the stars until it melted into the sky.
"Whoom!"
"He is looking for us," said Blackie; "stand by your hangars."
To the northwest two swift beams of light were sweeping the sky urgently. From a point farther south sprang another beam.
"If Fritz doesn't locate us now he ought to be shot," growled Blackie.