Camped!Lynn Loud Sr. is saddened over the fact that Camp Mastodon on the shores of Lake Michigan is closing. This camp is where Lynn Sr. went with his father Leonard. Lincoln suggests to his sisters that they should visit Camp Mastodon with their father before it closes. Flip is also present for its closing due to him having also attended this camp and the family meets with its owner Mr. Rinsler who states that he can't keep paying to keep it opened. While cleaning out Mr. Rinsler's cabin, Lincoln finds a map for the treasure of Captain Kit that he buried after the Great Lakes Storm of 1913. This causes Lincoln and Lynn Sr. to lead the family into going on a treasure hunt as they are secretly followed by Flip and contend with various obstacles along the way.