Locked On is a techno-thriller novel, written by Tom Clancy and co-written with Mark Greaney, and released on December 13, 2011. A direct sequel to Dead or Alive (2010), it is Clancy's first of three collaborations with Greaney and features Jack Ryan Jr. and The Campus as they try to avert a nuclear threat from a rogue Pakistani general, as well as his father Jack Sr. in his presidential campaign. The book debuted at number two on the New York Times bestseller list.