. . . but you won't get a bang out of it. The title refers to the marked boxes that move in with the Bubblefins; the ubiquitous-eccentric neighbors wait for an explosion that never comes (primarily because the cases contain underwear). Meanwhile, Bubblefin the inventor is commissioned to build a machine enabling Professor yon Sweetwater to hear fish singing but his attempt is a bust: he blows the advance on party food, substitutes odds and ends contributed by the neighbors, finds to his dismay that he has built a monster of sorts--the sort that echoes every sound. . . except fish singing. The two Johnnies (twins whose travelling father won't bother with two names) accidentally stumble onto a solution when they stumble into the machine: their weight transforms the amplifier into ""a machine that makes silence."" It's a situation that sounds fishy from the start and its development is dependent on coquettish enunciation instead of on incident.