Don't worry, it's a B-24 bomber from World War II. (One of fewer than a handful that are left—after a wartime production of 10,000).
Surprised at about 5:35, I heard its deep droning before I saw it flying directly over Tuftonboro Neck. There must be a show at Laconia, but I've seen nothing on the Internet about it.
The last one I saw was banking steeply at about 800-feet
towards me—above Florida's Sebring International Airport (and Raceway).