The Hardy Boys, Undercover Brothers
#19, Chaos at 30,000 Feet!Book - 2009
When inner city kids are gifted pilot lessons from a flight school, several of them go up but don't come down! Where did they go? Where did they land? Could they not have landed at all? Joe and Frank take to the skies in this high flying adventure as the undercover brothers seek get to the bottom of this mystery... even if they have to sail the clouds to get the answers!