While on summer vacation, little Irene Adler meets a young William Sherlock Holmes. The two share stories of pirates and have battles of wit while running wild on the sunny streets and rooftops. When Sherlock's friend, Lupin, joins in on the fun, they all become fast friends. But the good times end abruptly when a dead body floats ashore on the nearby beach. The young detective trio will have to put all three of their heads together to solve this mystery.