A noble girl named Lydia calls on the Defenders for help when she is suddenly attacked by the Amphitigons; Mel, Erik, and Adam rescue her but she tells them that the Amphitigons have stolen a precious Heart Stone and captured her brother. Seth and Rion are back to the Dojo, but while testing out the new mech arm Erik has made for his friend they are attacked by the Zads, who have managed to avoid the security system.