Shine of the silver dragon

Diego is under the spell of the wizard Maldred who wants to control the Naga, an enormous dragon that lives deep within the Earth, and plans to use Diego to steal the two keys necessary for that purpose; the first key is guarded by Argent, the silver dragon, and Jean his dragon master, so Drake, Bo, Carlos, and their dragons travel to Gallia to try and stop the theft and break the spell on Diego.