On his sixteenth birthday, William Hawk awakes like he would on any other morning - a teenage boy focused on girls, cars, and food. But, before he can even finish eating, everything will change. William's Change Agent III status activates at 12:27 p.m. on his sixteenth birthday, and, with that, his responsibility to save Earth from evil begins. Just months before, on her sixteenth birthday, Grace's Change Agent III status reveals a horrible truth: her malevolent twin brother, Roland, is actually Roivas, the dark master reincarnated. After years of being mistreated by her brother and deemed crazed and dangerous by her family, Grace finally encounters the opportunity to free herself from her brother's terror and save her planet. William and Grace must develop their connection with each other and their skills as Change Agents to stop evil from overtaking Earth. Seven of the ten worlds within the universe have defeated evil, but none have combated Roivas directly. With the help of family, Cy, Sonny, and friends from Earth and beyond, William makes sense of his new, pre-bio memories and overcomes past mistakes to bring Earth toward the freedom of Final Ignition.