Calvin Fuller is a typical teenager living in Southern California, with a love for skateboarding and a fascination with technology. One day, he falls through a crack in the ground caused by a freak earthquake and finds himself transported to the legendary kingdom of Camelot.
There, he meets the wise wizard Merlin, who informs him that he has been summoned to save Camelot from a powerful enemy – the evil Lord Belasco. Calvin is amazed to find himself in a magical world filled with knights, princesses, and castles. He soon discovers that he has been brought to Camelot because of his knowledge of technology and science, which Merlin hopes will help turn the tide against Belasco's forces.
Against all odds, Calvin sets out to help King Arthur and his knights defend their kingdom and foil Belasco's evil plans. Using a combination of his modern inventions and his clever wit, he invents weapons and devices that the knights have never seen before, including a skateboard that is transformed into a powerful armor suit and a water balloon launcher that takes out Belasco's army.
Along the way, Calvin falls in love with Lady Catherine, the beautiful daughter of King Arthur, and becomes embroiled in the politics and intrigues of Camelot's royal court. He also learns important lessons about honor, courage, and loyalty, as he strives to protect Camelot and its people from those who seek to do them harm.
In the end, Calvin's contribution proves crucial in the final battle against Belasco, and he earns the respect and admiration of all those around him. With the help of Merlin and King Arthur, he returns safely home, but not before imparting some of the valuable lessons he has learned from his time in Camelot to his modern-day friends and family.