Successful Houston veterinarian finds love again with younger doctor; Authorities set up an elaborate sting operation to catch a him after he convinces her they need to hire a hit man to kill their exes; Man speaks to 20/20 while he awaits trial behind bars.

Brother recalls the 2011 day he saw his sister, Holly, alive for the last time; Missing 20-year-old Tennessee nursing student Holly Bobo's remains are found by ginseng hunters; Jury returns with verdict in man's trial for Holly's murder.

Route 91 Harvest Festival underway in Las Vegas, filling open air plaza on The Strip with country music lovers as shooter prepares in hotel; Woman describes moment when husband was shot while holding her; Remembering the Las Vegas mass shooting victims.

Multiple women describe alleged encounters with Harvey Weinstein; Angelina Jolie, Gwyneth Paltrow claim Weinstein harassed them; What could happen next for Harvey Weinstein.

Twenty-seven years after a Florida woman was fatally shot on the doorstep of her home by an assailant in a clown costume, police arrest her husband's new wife.

Vegas gunman's motivation remains a mystery weeks after deadly attack; Conspiracy theories emerge in Las Vegas shooting; Vegas shooting survivors say they still have nightmares, trouble sleeping.

When former Marine discovered teen son talking to ISIS recruiters; How ISIS uses the internet to target young Americans for recruitment; The fight against ISIS's reach on America's youth.

Baillie Gibson becomes one of the best discus, shot put athletes in the country; College athlete, coach disagree whether sexual relationship was consensual; Former coach Craig Carter speaks out about Baillie Gibson case.

20/20 airs a very special episode that features Nathaniel Newman, a boy with the very rare cranio-facial condition Treacher Collins syndrome.

Peter Billingsley, the star of "A Christmas Story," discusses some of the most memorable and beloved Christmas movies of all time, including interviews with the stars, and behind-the-scenes looks at some of the most memorable moments from the films.

Accomplished fashion writer found stabbed to death at her home; Police ask men in Truro, Massachusetts for DNA samples in murder investigation; Chris McCowen shares his side of the Christa Worthington case.

Meghan Markle's engagement to Prince Harry; interviews with those who know Meghan; an in-depth look at Meghan's life, family, humanitarian work, and career.

Former members of NXIVM, a professional coaching company, speak out about their experiences in the alleged secret society, NXVIM's litigation tactics against former members and critics.

Mom says daughter suffered from illnesses and needed wheelchair, feeding tube; Gypsy Blanchard on what happened the night mom was stabbed to death; Man says he feels ex-girlfriend used him to kill her mom.

A woman convicted of killing her husband claims she was blacked out during the murder that she says occurred during a home invasion.

Interviews with people involved in the case of Shanann Watts, who was pregnant when she was murdered by her husband, who also killed their two young daughters.

The gymnastics sexual abuse scandal that included accusations by Olympic gymnasts continues to dominate headlines as an astounding 156 women have testified against ex-USA Gymnastics doctor Larry Nassar.

Slender Man stabbing: Parents recall what happened that morning; 12-year-old survives being stabbed 19 times by her friends; What is Slender Man, the figure that motivated two girls to stab their friend.

Prominent Virginia couple found brutally murdered in their home; Detectives question daughter of couple found murdered and her boyfriend; Boyfriend, girlfriend travel to Europe during murder investigation.

"20/20" features the stars of the most influential romantic movies, takes viewers behind the scenes and dissects the most memorable moments from these classics. The special will feature interviews with actress Katherine Heigl, from "27 Dresses"; Nia Vardalos and Andrea Martin from "My Big Fat Greek Wedding"; and Dakota Johnson and Jamie Dornan from the "Fifty Shades" films.

Actors Roseanne Barr, John Goodman, Laurie Metcalf, Sara Gilbert, Lecy Goranson, Michael Fishman, and Sarah Chalke reveal behind-the-scenes moments, memories, and discuss the show's legacy.

A fatal kayaking trip is the focus of an interview with Angelika Graswald, a woman who was convicted of involuntarily killing her fiancé, after the kayak sank on the Hudson River in New York in 2015.

A son orchestrates a murder-for-hire plot that injures him and kills family members; the son is convicted of first-degree murder and sentenced to death; the son's father pleas for the death sentence to be commuted to life in prison.

Woman dies mysteriously in historic California mansion; Dead woman's family refuses to believe she committed suicide; Nearly seven years after mysterious death, civil trial begins.

Sharon Morello and Howard Burack were both adopted as babies, and they each later learned they had an identical sibling from whom they were separated as infants.

Two women suspect they may be the five-month-old infant who disappeared from her crib over twenty years ago, and DNA testing is used to determine if one of them is the missing baby.

ABC News' Amy Robach sits down for the first interview with Denise Huskins and Aaron Quinn, center of the so-called "Gone Girl" case, whose kidnapping was initially dismissed by authorities as a hoax.

Recently divorced woman starts dating man with a troubled past; Man, girlfriend allegedly behind murder-for-hire plot to kill their exes; Arrested for alleged murder-for-hire of their respective exes.

A mother opens up about her fight to prove her son is innocent of murdering Mark Fisher, a 19-year-old college sophomore on the dean' list, viciously beaten and shot five times on Oct. 12, 2003.

Strikes will establish a strong deterrent of chemical weapons: Trump; Pentagon officials remark on strikes in Syria.

The event America's been waiting for - James Comey - his first interview since being fired by President Trump.

Sexual harassment in the workplace and potential solutions.

Woman recalls being branded as part of joining secret society; What former NXIVM members say about Keith Raniere's attitude toward women; How 'Smallville' actress became involved with NXIVM.

Authorities use DNA to find Joseph DeAngelo, the suspected Golden State Killer; interviews with attack survivors and others close to the case.

A midflight explosion forces pilot Tammie Jo Shults to make an emergency landing in Philadelphia; interviews with passengers on the flight and those that know the heroic pilot.

Memorable moments from Prince Harry and Meghan Markle's wedding, including the vows, reception, fashion, and the royal couple's first public appearance as man and wife.

A behind-the-scenes look at summer blockbusters; the 25th anniversary of "Jurassic Park"; "Animal House" cast reunion.

Reports on ankle bracelet monitoring failures and murders committed by people ordered to wear them.

Woman's sudden death raises family's suspicions; Sheriff acknowledges missteps in handling dead woman's case.

Mom discovers daughter brutally attacked by man with shovel; Attack survivor undergoes hypnosis to remember details about assault; DNA match links man to near-fatal shovel attack.

When a woman secretly records her husband's affair, she snaps and kills his girlfriend and herself.

Drug Enforcement Administration (DEA) agents Eric Triana and James Mannick and NYPD detective Danny Politowski help carry out a sting operation where women secretly drug and rob wealthy men; interviews with Jennifer Lopez and Cardi B of "Hustlers."

Adults abandoned at birth turn to genetic genealogy to find biological family; Adults abandoned at birth meet biological family members for the first time; Woman meets biological sister for first time.

Parents fear for young daughter's safety as her behavior changes dramatically; Rare disorder may explain 11-year-old's sudden odd tics and moodiness; Why is PANDAS so controversial?

Thai cave rescuers say they expected some kids to die during the mission; Mission is a 'go': Rescuers jump into action to save boys from Thai cave.

A look back at the life and legacy of musical legend Aretha Franklin; never-before-seen video of Franklin on tour; interviews with those that knew and worked with her.

An in-depth look at the legendary public, professional and personal life of Sen. John McCain (R-Ariz.).

A junior soccer team is trapped in a cave for days, waiting to be rescued.