What unexpected event occurred at the beginning of the 2. chapter?

From the top of her pole, Cassie sees Papa and another man coming down the road. The children rush over to hug them, and he says they're getting too big to call his "babies" anymore. The other man with them is Mr. Morrison, who is very tall. He has burn scars on his face and neck, deep wrinkles, some gray in his hair, and "clear and penetrating" eyes. Mama wants to know if something is wrong, but Papa avoids the question.