After catching Regigigas in the Snowpoint Temple not long after being crowned the new Champion of the Sinnoh League, Lucas uncovers a long forgotten tomb containing a strange flute, a notebook filled with strange Pokèmon, and a tablet with arcane script written upon it. After consulting Cynthia and Dawn about his discovery, Lucas learns that he has discovered the tomb of the ancient Pokèmon researcher Rei Teru, and learns the tale of the very first Pokèdex.