The Hitchhiker's Guide to the Galaxy deserves a special place in the geek pantheon. It's the story of hapless BBC radio editor Arthur Dent, his best friend Ford Prefect, and the adventures that result when Prefect saves Dent when the Earth is unexpectedly destroyed to make way for a galactic bypass. Written by the late, great Douglas Adams, HHGTTG first appeared as a radio series in the UK back in 1978. On Thursday—exactly 40 years to the day from that first broadcast—it made its return home with the start of Hexagonal Phase, a radio dramatization of the sixth and final book of an increasingly misnamed trilogy.

Adams' original radio series went on to spawn a universe of works. From that initial six-part series came the novel The Hitchhiker's Guide to the Galaxy, then a re-recorded LP, a second novel (The Restaurant at the End of the Universe), a second radio series, a TV series, another two books (Life, the Universe, and Everything; So Long and Thanks for All the Fish), a computer game, a short story (Young Zaphod Plays it Safe), and then a fifth book (Mostly Harmless). And the ideas Adams wrote about were visionary: what else is your smartphone if not a real-life version of the Guide?

Although Adams died suddenly and unexpectedly in 2001, the universe he gave birth to lived on. Beginning in 2004, the original radio cast was reunited to dramatize the third, fourth, and fifth books. In 2005, a film adaptation was released, and then in 2009 came a final novel in the "trilogy," And Another Thing..., written by the novelist Eoin Colfer. It's this story that the BBC is now dramatizing, again using many of the original cast, along with newcomers like Jim Broadbent, Lenny Henry, and Stephen Hawking. Yes, that Stephen Hawking.

(OK, hardcore Hitchhiker's fans will want to point out that BBC Radio 4 broadcast an audio adaptation of And Another Thing..., read by Stephen Mangan (who went on to play Dirk Gently in its first TV adaptation) and Peter Serafinowicz, back in 2009. Consider that done.)

Adams' work in all its various forms has always meant a lot to me. It's the first novel I can remember reading, although I can't tell you if that was before or just after I saw the excellent BBC TV series back in 1981. It even taught me to accept "canon shock," which is when the same general story appears differently in different formats; there are significant differences in the plots of the first two radio series compared to the books (compared to the TV series and compared to the film). And it's hard not to feel a shiver when I hear the twanging banjo of its opening theme "Journey of the Sorcerer."

So I'm happy to report that this latest installment doesn't disappoint. And even better, unlike the BBC's TV content, it's not geoblocked or behind any kind of paywall. So go on, what are you waiting for—the coming of the Great Prophet Zarquon?