[1] Produced by Hanna-Barbera and based on the classic Mark Twain characters, the program starred its three live-action heroes, Huck Finn (Michael Shea), Becky Thatcher (LuAnn Haslam), and Tom Sawyer (Kevin Schultz), navigating weekly adventures within an animated world as they attempted to outrun a vengeful "Injun Joe" (voiced by Ted Cassidy).

[3] Also nearing the end of post-production at the time was Hanna-Barbera's Jack and the Beanstalk, an hour-long special which featured Gene Kelly dancing alongside various cartoon characters and aired on February 26, 1967.

[4][8][9] In a July 1967 interview with columnist Hal Humphrey, William Hanna expressed high hopes for the innovative new concept, saying "When you say the word 'cartoon', people think of children only, and we limit ourselves – although plenty of adults watch cartoons.

We think combining the live action with the animation will give our company a special identification," with Joseph Barbera adding, "And do you know the clothes from that period are 'mod' today?

"[6] In casting their lead, Hanna-Barbera and NBC eventually found their ideal "Huck" in 14-year-old veteran child actor Michael Shea, reportedly selecting him out of 1,300 boys.

At the time, Schultz was best known for starring on the television western series The Monroes alongside his twin brother Keith, who had reportedly also auditioned for the role of "Tom" before Kevin was selected.

In an August 1967 interview with columnist Mel Heimer, Cassidy stated that he was looking forward to his upcoming role on the new series, saying, "I think I'll get more of a chance to do some acting than I did in (The Addams Family).

"[10] The live actors' scenes were filmed in front of a royal blue backdrop (an early forerunner to the modern-day CGI green screen) and the cartoon background and characters were animated in later.

Shea recalled, "Injun Joe, for instance, was a cartoon character, so when I had to talk to him, I'd run my eyes slowly up the blue screen until the director told me to stop.

Next, we see our three protagonists, Huckleberry Finn (Michael Shea), Becky Thatcher (LuAnn Haslam) and Tom Sawyer (Kevin Schultz) taking a shortcut home through the town's graveyard, where they encounter "Injun Joe" (Ted Cassidy).

[5][12][16][17][18][19][20] Although we never see the three youngsters emerge from the cave, it is presumed that they eventually find a way out since, as each episode proper begins, we join our three young live-action heroes as they now inhabit an animated world.

Throughout the series, the children embark on a quest to return to their families in Hannibal, Missouri, traveling to various exotic animated lands (tropical islands; Egyptian deserts; Aztec cities; etc.)

The likeness is not lost on the three children, who are routinely startled by the striking similarity to their nemesis back home; however, no explanation is offered of how, or why, Injun Joe is constantly able to remain one step ahead of them and assume these various guises.

[18][19] Initial reaction was generally positive, with critics praising Hanna-Barbera's technique of combining live-action with animation as well as the performances of the show's three young leads.

"[20] As a Sunday evening show, the series garnered a wider audience than Saturday morning cartoons of the time, and launched its three attractive young stars as popular teen idols of the day.

Although popular with child and teenage audiences, the series struggled in the ratings against its Sunday night competition (Land of the Giants on ABC and Lassie on CBS), by the end of 1968, news sources were already reporting that a second season appeared unlikely.