the answer
Mrs. Stearns had taken the signs.
There was no evidence to show that Paul had actually used his truck to transport the signs. The boards used for Freddie's tree house were too old and worn to have been recently used for the signs. But Mrs.Stearns had a fire in her fireplace on a hot July day. She didn't want neighbors close by, and so she had taken the signs and was burning them in her fireplace so nobody would know the house was for sale.
"That fire was a hot tip," Nina said later as she joined Max and Mrs. Decker for a cold drink of lemonade.
kudos gets 8
(did not explaiend it)
raveensach 5
harshlife 3