Constable Hyung-rae and the Three Insect Muskateers

Sol-i and Song-i head to Hanyang with the blueprint for a cannon invented by their father. On the way, they meet Japanese pirates and get captured, but Baek Du-geon appears and defeats the pirates and saves Sol-i and Song-i. Sol-i and Song-i arrive in Hanyang and hand over the blueprint to Hong Cham-pan, and Baek Du-gu…