What does Tom discover in the garage of his new home in Featherbank in the novel, The Whisper Man?

After he sees Collins trying to break into the garage, Tom goes out to the garage for the first time and discovers the junk from the house has been stored there. He also sees unusual butterflies in the garage. The second time Tom visits the garage, he discovers the box containing Tony Smith’s remains hidden in the bricked-up portion of the floor.