Many of the shows were unintentionally hilarious. Their "investigation" of the Bermuda Triangle hinged upon an obvious prank call to a radio station. Many episodes also dealt with ancient civilizations, conspiracy theories surrounding historical conundrums, or New Age trends like talking to plants. The most informative ones speculated on the future of science and foresaw the coming of cloning and stem cell research.
Some of the subject matter dates itself. Remember the coming ice age? A Killer Bee Invasion from Mexico? I believe they also predicted a fire ant invasion. Thankfully we are not having snowstorms in July or living in domes to escape the bees! NOT YET ANYWAY!!
In Search Of is not only a splendid time capsule of its era, but a forerunner of the future shows like The X Files and the ever popular late night radio show Coast to Coast AM (night owls know what I'm talking about). In its own unique way, In Search of played a crucial role in inventing an entirely new genre of popular culture.
Leonard Nimoy made for the perfect host. Who better than Mr. Spock guide you through all the strange mysteries? His calm and detached narration brought calming effect to the program.
Episodes often weaved between real science with pseudo-science. Each show made it clear the producers were only suggesting solutions, not definitive answers. Many of the topics still recur on mystery/documentary shows such as UFO's, ancient prophecy, and crypto-biology. For a sort of cult history of the late 70s and early 80s, In Search of provides plenty of intriguing subject matter.
Thankfully, the show never took itself too seriously. Usually In Search of gave equal time to believers and skeptics alike. At the end of the day it was great fun. Also, there's nothing like the theme music, such sounds could only emanate from 1977.
A brief revival appeared in 2002 on the Sci-Fi channel with Mitch Pileggi as host, those episodes are included in DVD package as well.