Ben left Kai's mother when Kai was born, as Ben sensed Kai's aptitude for using the Omnitrix would clash with his and cause danger. Kai is sent a mysterious package for an early birthday present and told not to open it until he turns 16.... in ten days.
Kai is partying four days before he turns 16, and something causes the block to fall, sending everyone into curiosity. The Omnitrix is used, and Kai wants to know where his mother is.
Kai and Fole are sent on a mission to bargain with Gooba the merchant to get a precious artifact before being trusted to go on a dangerous search mission. However, everything in the world of the Plumbers is more difficult than it seems.
Kai meets some colleagues of his dad, and learns of his current mission - to help Earth become more technologically advanced. Kai also learns something he wishes he could forget.
Kai and Fole meet a man in Newcastle who is obsessed with Vulpimancers. He keeps them captive and treats them unfairly, taking some of their DNA to aid his own transformation into a Vulpimancer/Human hybrid.
Kai decides that taster of alien combat was enough for him, and goes out, finding a girl, asks her out, and tries to preserve what is still normal in his life. Others decide, that, that isn't happening.