Return of the Librarian: 13 Hangmen by Art Corriveau

An old baseball cap.  A bunch of 13-year-old boys who've lived in the same Boston townhouse at various times throughout the last three centuries.  An evil neighbor whose family has been scheming to get hold of the house for just about that long.  Here's a mystery from history.  Tony DiMarco's great-uncle Angelo, who he only met once, leaves him an old townhouse and an antique baseball cap when he dies.  The will requires that Tony live in the house until he reaches legal adulthood.  Moreover, he must sleep in the attic, a ratty, unfinished space.  The whole house at 13 Hangmen Court is crumbling (welcome to the embodiment of " desperately needing deferred maintenance").  The old man next door, Mr. Hagmann, claims Tony's father murdered Zio Angelo.  Life is just full of surprises lately, few of them good.  One night, Tony places the old baseball cap on an oddly carved stone shelf in his room.  When he wakes up, he finds he's sharing the bed with another 13-year-old boy, who says his name is Angelo, it's 1939, and this is his room.  And that he's just received the very ballcap Tony was recently gifted with for his thirteenth birthday.  Supposedly, it belonged to a famous Red Sox outfielder named Ted Williams.  Tony and Angelo begin piecing things together, trying to figure out why Mr. Hagmann, and his father, and grandfather... have been attempting to get their oily mitts on the ramshackle townhouse for centuries.  What kind of treasure could be hidden within?  How do they prove that Tony's dad didn't murder his uncle?  Will Tony's mother ever quit pestering him about eating healthier and exercising/losing weight?  Read 13 Hangmen by Art Corriveau to find out.  You'll wish you had a strangely carved shelf in your room, too.  Oh, and BTW, the molasses flood really happened.