A year after Nya's transformation, the ninjas come together again to investigate the smuggling from Deepstone. The five must rely on the help of Aspheera, who is imprisoned in the Cryptonite prison because of them. Additionally, they encounter unknown new ninjas who increasingly threaten to outmatch them. However, in the background, a much larger and more mysterious danger is brewing. Meanwhile, Nya is trying to regain her old form to return to her friends. Will she succeed, and if so, at what cost? What is the mystery behind the Diamond King, and can our heroes overcome their seemingly insurmountable challenge?.