When the Appleby′s crewmen go on shore leave in Japan, Lieutenant Commander Stoner places them under strict orders not to return to the ship with any souvenirs too large to fit in a footlocker, posing a problem for Lieutenant (junior grade) St. John: He promised to buy an antique Japanese cannon for his girlfriend and has smuggled one aboard the Appleby, and he has to figure out how to hide it from Stoner.