Spawned from a series of prime-time missing-persons specials in 1985, the original "Unsolved Mysteries" laid the foundation for the modern true-crime phenomenon, turning regular citizens into detectives. Unlike the news broadcasts of its day, the show urged viewers to get involved and call in with tips, leading many of the cases to be solved with the help of everyday people.

Since its heyday in the late '80s and '90s, imitators have come and gone, but "Unsolved Mysteries" remains. With Netflix rebooting the series, here's what to know before watching.

The history: It began in 1985 as a series of three specials — basically televised versions of milk carton alerts — titled "Missing ... Have You Seen This Person?" Raymond Burr (aka "Perry Mason") hosted the pilot of "Unsolved Mysteries" in January 1987. The next year, NBC turned the program into a weekly offering with Robert Stack (aka "The Untouchables" Eliot Ness) as host.

After nine seasons on NBC, the show was canceled and picked up by CBS. But it didn't last and was claimed by Lifetime, where it played until 2002. In 2008, Spike TV repackaged old segments instead of producing new ones, an approach that confused viewers by presenting cases that were no longer unsolved. It was canceled in 2010.

The influence: As the show rose in popularity, the way television covered true crime changed. Viewers became amateur crime solvers as "Unsolved Mysteries" and its partner in prime-time crime, Fox's "America's Most Wanted," became ratings hits. Other shows followed suit. Programs like "48 Hours" and "Dateline NBC," originally formatted as newsmagazines, began to focus more on criminal cases. The shows' attraction presaged the kind of true-crime obsessiveness found today on internet message boards and in the rabid fan bases of podcasts like "Serial" and "My Favorite Murder."

The cameos: A hallmark of the series became the re-creations of horrific crimes. Most of the performances in these dramatizations wouldn't make an actor's highlight reel, but familiar faces popped up throughout the run of the series. Matthew McConaughey played a man who was murdered, and the future "Hawaii Five-0" star Daniel Dae Kim appeared briefly as a victim's brother-in-law. Other familiar faces included those of Taran Killam ("Saturday Night Live") and Jim Beaver ("Supernatural," "Deadwood").

The cases: Over hundreds of episodes, the series covered mysteries ranging from alien abductions to the Zodiac killer — no case was too big, small or outlandish — often shining a light on cases that might otherwise have been forgotten. And in the decade since the show went off the air, unsolved cases have continued to find life on its website, which still serves as an information portal — and a tipster hotline — for armchair internet sleuths.

The return: Times have changed, which means the show must, too. The 24-hour news cycle has changed what can rise above the din. As a result, the show focuses on a single mystery instead of several, and the production is much more cinematic. But the basic spirit hasn't changed. Every episode still ends with a call to action. Maybe you can solve a mystery.