In their hometown of New York City, twin fifteen-year-olds Tom and Mitchspend their free time skateboarding and reading comics. But one day theyget attacked by a thug in ninja gear, and the secrets that have been kept from them for years are suddenly let loose. They learn that their father and live-in butler are members of a rogue crime-fighting organization, R.O.N.I.N., which dates back to feudal Japan; that their father is in danger; and that they have just been recruited to join their father's clan. These brothers are in for an adventure of a lifetime.