The fourth season of NCIS begins as team leader Callen (Chris O'Donnell) tries to clear himself of charges implicating he murdered a suspect in cold blood, while operations manager Hetty Lange (Linda Hunt) faces a threat from her past. The rest of the team, meanwhile, double their efforts to track down a dangerous terrorist despite uncovering a secret that puts those closest to former Navy SEAL Sam Hanna (L.L. Cool J.) in danger.
In this update of Washington Irving's classic tale, Ichabod Crane (Tom Mison) wakes up in the 21st century but finds his 18th-century nemesis, the Headless Horseman, has also come along for the ride. After a local sheriff (Clancy Brown) is killed, Crane teams up with Det. Abbie Mills (Nicole Beharie) to sort out the mystery and its historical implications, though her supervisor, Capt. Frank Irving (Orlando Jones) is skeptical of all the supernatural shenanigans. And as Season 1 unfolds, these otherworldly events include encounters with menacing demons, frightening explorations of purgatory and impending visits by the Four Horsemen of the Apocalypse.