Dateline: Unforgettable Season 3

Keith Morrison recalls how a deadly high-speed chase in Montana led to a mystery, where a missionary turned into a monster and committed one of the state's most notorious crimes.

A mystery in paradise unfolds when Sarm Heslop vanishes from her boyfriend's yacht; in a case that made international headlines, Andrea Canning recounts her memorable journey searching for a particular person of interest.

A 911 call reporting an apartment break-in holds the key to solving the mysterious murder of a young graduate student named Katie Sepich; her case contained many twists, and her family's grit still astonishes Josh Mankiewicz.

When Tina Sandoval disappears, her parents and loved ones spend years searching for her; Dennis Murphy takes a fresh look at the secret Tina kept and at the demon who forced her loved ones to make an agonizing decision.

The survivor of a horrible attack is convinced the police on the case have the wrong suspect. Keith Morrison looks back on his heart-wrenching interview with the victim and her courageous quest to uncover the truth.

After Todd Chance is murdered, police follow a trail of video evidence to track down their suspect; Andrea Canning recalls a particularly revealing interview, including an eye-popping detail.

When Josh Mankiewicz gets asked about his most memorable stories, the name Dayna Herroz comes to mind; after her daughter and 10-month-old grandson are murdered, her quest for justice ends with a twist in a San Diego courtroom.

A Florida father is determined to find out what happened to his daughter after her fatal fall from a penthouse apartment; Dennis Murphy revisits the dramatic events as this dad confronts overwhelming obstacles to learn the truth.

When three people are found dead on the same day in a Kentucky town, investigators know that it isn't a coincidence; years pass before an arrest; Keith Morrison reflects on the triple murder that shook a tight-knit community to its core.

The fatal shooting of NBA star and hometown hero Lorenzen Wright sends shockwaves through the city of Memphis, TN; Andrea Canning takes a new look at the diabolical plot behind Wright's murder and his family's tireless fight for justice.

The murder of 19-year-old Alaska Native Sonya Ivanoff jolts the small coastal city of Nome, Alaska; the story sends Josh Mankiewicz to the most remote place he's ever been for "Dateline."