Turncoat follows the story of Duke, the world's worst superhero assassin, and his constant battle with his ex-wife-and-rival assassin, Sharon. Duke is always one step behind Sharon, constantly missing out on the "big hit" that will set him for life. (It certainly doesn't help matters that he only ever seems to go up against D-list superheroes like "Bug-Boy" and "Freedom Fighter".)
...so when Duke receives a contract for the most famous superhero team in the world, he realizes his time has come. Not just to finally make the big hit, but to finally move on from his ex-wife.
If only it were that simple.