A review by barefootsong
The House on the Cliff by Franklin W. Dixon

3.0

Smugglers, secret passages, and ... a boat explosion! (The boat explosion is noteworthy because of a throwaway line [in ND#1]. Apparently boat explosions were a concern in the 1920s and/or 1950s, depending on if the boat explosions are present in the original texts.) Everyone, good or bad, is pretty dumb, but amusingly so!

There was only one picnic in this one, but it was a surprise picnic ... on a boat! (Not the boat that exploded!) And of course the picnic included cake.