There was a peculiar hemispherical hump protruding above the general level of the upper surface of the smoke cloud. It looked like a mushroom thrusting its top through the ground. As they came nearer they could see that there was a violent disturbance of air around that hump. The smoke had a golden glow which indicated a fire beneath. The much needed data could never be obtained without dropping through the cloud. With the troubles and dangerous flying conditions which Bill had encountered above the last fire still fresh in his mind, Bill hesitated about plunging down into the unknown.