Greg is mad at hid Dad because he can not play for the Scorpians because of his grades in math. So instead of studing he decides to go into the town and goes into a abandoned house because it is raining
Inside the house Greg meets Lemon brown and the discuss treasures. But later thugs attack the house so they hide upstairs.
Greg and Lemon hide upstairs for a little while until the thugs find them so Lemon decides to attack the thugs while there distracted by jumping down the stairs at them. After the thugs ran away Lemon Brown reveals that his treasure is a harmonica and newspaper clippings. Afterwards Greg goes home to his dad.