Letters and Numbers - Season 4

After achieving success in her younger years, the brilliant septuagenarian Madeline Matlock rejoins the work force at a prestigious law firm where she uses her unassuming demeanor and wily tactics to win cases and expose corruption from within.

Tracker features lone-wolf survivalist Colter Shaw, who roams the country as a "reward seeker," using his expert tracking skills to help private citizens and law enforcement to solve all manner of mysteries while contending with his own fractured family.

Based on the iconic Leaphorn & Chee book series by Tony Hillerman, Dark Winds is a psychological thriller that follows two Navajo police officers in the 1970s Southwest, as their search for clues in a grisly double murder case forces them to challenge their own spiritual beliefs and come to terms with the trauma of their pasts.

NCIS (Naval Criminal Investigative Service) is more than just an action drama. With liberal doses of humor, it's a show that focuses on the sometimes complex and always amusing dynamics of a team forced to work together in high-stress situations. Leroy Jethro Gibbs, a former Marine gunnery sergeant, whose skills as an investigator are unmatched, leads this troupe of colorful personalities. Rounding out the team are Anthony DiNozzo, an ex-homicide detective whose instincts in the field are unparalleled and whose quick wit and humorous take on life make him a team favorite; the youthful and energetic forensic specialist Abby Sciuto, a talented scientist whose sharp mind matches her Goth style and eclectic tastes; Caitlin Todd, an ex-Secret Service Agent; and Timothy McGee, an MIT graduate whose brilliance with computers far overshadows his insecurities in the field; Assisting the team is medical examiner Dr. Donald "Ducky" Mallard, who knows it all because he's seen it all, and he's not afraid to let you know. From murder and espionage to terrorism and stolen submarines, these special agents travel the globe to investigate all crimes with Navy or Marine Corps ties.

History's Greatest Mysteries will investigate a wide range of historically compelling topics and the mysteries surrounding each including the Titanic, D.B. Cooper, Roswell, John Wilkes Booth, and more. Each program within the franchise will showcase fresh, new evidence and perspectives including never-before-released documents to the general public, personal diaries and DNA evidence to unearth brand-new information about these infamous and enigmatic chapters in history.