Son of Merlin

The wizard Merlin finds human magician Gwen tied up in a New York warehouse. He uses magic to release her only to find himself trapped in a binding circle. Gwen escapes before enchantress Morgana le Fay enters and kills Merlin. She tries to retrieve Merlin's diary from his body but it vanishes. At MIT, Merlin's diary appears in Simon Ambrose's lab. Gwen later approaches him and tells Simon that Merlin is his father, but they're interrupted by Morgana's Black Knights.

Gwen and Simon narrowly escape the Black Knights and flee to one of Merlin’s safe houses. Gwen trains Simon how to heal himself, use telekinesis, and shapeshift. Another Black Knight, Ywain follows them to the safe house and attacks Simon and Gwen.

Simon stuns Ywain by using telekinesis long enough for him and Gwen to escape through a secret exit and trigger the self-destruct sequence. In order to get the Stone of Giramphiel before Morgana, Simon shapeshifts and sneaks into Le Fay headquarters. A barely-alive Ywain returns to Morgana and tells her of Simon’s magic powers. Simon finds out that Morgana has been searching for the stone in Istanbul. He goes with Gwen to her mother Penelope’s house for the night without realizing Morgana is watching them.

Morgana attacks Gwen and Simon while they sleep. Accepting they're overpowered, Simon agrees to give her Merlin's diary in exchange for their safety. Simon and Gwen travel to Istanbul and enter a cave full of Morgana's Black Knights. Merlin's ghost appears and guides Simon towards The Stone of Giramphiel but also warns him of three elements protecting it. Simon lifts a giant rock to pass the first safeguard, but water fills the cave and Simon admits he can't swim.

Simon finds an underwater passage that leads to The Stone of Giramphiel in ring form. He and Gwen fight and defeat the third element, Fire Wraiths, only for Black Knights appear. Simon puts on the ring and uses its power to escape into another realm but leaves Gwen with Morgana. He confronts her at Stonehenge and agrees to use the combined power of his ring and Merlin's diary to help Morgana summon Keres to devour all of humanity. Simon quickly betrays her by instead summoning Keres to kill Morgana. With Gwen safe, she and Simon search for the most recent incarnation of King Arthur.