Ayreon is less a band and more of a prog-music project—each Ayreon album is a “rock opera” composed by Dutch musician Arjen Lucassen. Lucassen then assembles a cast of top-notch singers and musicians (often recognizable faces from the prog-rock scene, but sometimes relative newcomers as well) to play all the parts in the musical drama.

The Human Equation is the latest Ayreon project, and it’s one of the most rewarding albums I’ve listened to all year. Unlike most Ayreon rock operas, which tend to involve elaborate (and somewhat cheesy) sci-fi and fantasy storylines, Equation tells a much more personal and grounded story: a man who has fallen into a coma after an accident (…but was it really an accident?) relives milestones in his life, confronts his guilt and other personal demons, and works his way to an understanding of what really happened.

The storyline is not staggeringly innovative, and is a bit difficult at times to follow, but that’s OK: it pales before the music, which positively soars. Lucassen is a prog-rock musician at heart, which means Equation has a good share of pounding guitars and space-age synthesizers, but he pulls out all the stops to make this album a diverse one. Depending on the subject matter at hand, the music ranges from heavy and serious to light and breezy; instruments ranging from violins and cellos to flutes to bassoons to a didgeridoo weave in and out of the album throughout its 100-minute playing time. The singers Lucassen cast are great: James LaBrie (of Dream Theater) has the part of the main character, Marcela Bovio plays his wife, and a slew of other vocalists show up as different voices from the main character’s past and subconscious.

All of the songs are tightly focused around the album’s concept; it’s the sort of album that really demands a full-length listen to really appreciate it, although several of the songs quite well on their own. “Day Two: Isolation” (download it from the Ayreon site) opens the album with a terrific, guitar-heavy intensity; “Day Seven: Hope” is a lighthearted, nostalgic song perfect for cranking up on a summer road trip; “Day Eleven: Love” swings majestically from dreamy vocals to hammering guitars and back; “Day Seventeen: Accident?” flirts with an ambient electronic keyboard groove. Most songs feature at least two or three different characters (male and female) singing in dialogue, which keeps the vocals varied and interesting.

If I sound like a raving fanboy, I suppose I am: I loved this album. It hits most of the spectrum of progressive rock, from crunching guitars to quiet flutes, from cookie-monster growling to ethereal female vocals. (It does ultimately lean toward the heavy side, though.) There’s a great deal of musical creativity packed into this one. I’d heartily recommend it to anybody who wants a good introduction to prog rock, or to anybody who just enjoys hearing a troupe of highly skilled musicians all doing what they do best.