Dirk

Twelve-year-old Dirk is one of the main characters of the Mystery of the Crystal Castle. Dirk and his younger twin Petra meet the siblings Christina and Grant at the Crystal Castle and help them solve the castle's mystery. They manage to solve it once they put all the pieces of their clues together, not literally, and use a map that Grant had found at the airport, find a chest with a royal seal! Grant had found a key in a secret room in the Singer's Hall, using it they unlocked the chest and found the pearl necklace that had been missing!