"Sandcastle Royale" is an episode of Special Agent Oso.
While Oso And U.N.I.Q.U.E. lumber through the forest following Agent Lead Researcher's footprints, a special alert is called. A girl at the beach, named Katie, is going to build a sandcastle as a surprise for her mother, only she doesn't know how. It will be up to Oso to help Katie make the sandcastle before her mother finishes reading her book.