A group suspected of criminal activities has established a colony on the outskirts of town. Robin Carruthers, flight school operator, and Rev. Forsyth, the rector of the Anglican church, become embroiled in a controversy when a bus used by the colony to transport children crashes into a frozen lake. Two women from the colony seek help from Robin and Douglas. One is murdered and the other nearly so, and Robin's planes are sabotaged.
Robin suspects a problem student of being the saboteur, but she has no proof. If she is right and does nothing about it, she could lose her business and her life. If she is wrong and reports her suspicions, she could ruin the student's life. So she watches and waits.