“Tidal Creatures” is the third installment in the “Alchemical Journeys” fantasy series conjured up by prolific Seattle author Seanan McGuire.

Right up front, I’ll acknowledge that wading into this series by starting with the most recently published book in the series wasn’t the smartest way to approach this complex brew of alchemy, mythology and unbridled ambition.

It was like stepping into a riptide that churned between serpentine storylines and characters as startling as the bizarre deep sea creatures that sometimes get thrown up onto the beach after a winter storm.

Nonetheless, that’s where I found myself last week — not out on the beach, but sucked into a story with assorted lunar deities and their human host bodies, a bright-orange hind “adjunct” that escapes the secret lab where it was assembled by alchemists, and a dastardly plot to control the Impossible City.

It would have been easier to navigate the story if I’d first read the previous two books in the series, “Middlegame” and “Seasonal Fears.”

But even without having done that, I was spellbound by the storytelling, which is elegant, languidly assured, and sometimes heart-poundingly sinister.

And once Kelpie (the neon-orange deer) escapes her makers and finds unexpected refuge in the home of an hechicera — a sorceress with Latin American roots — there was enough exposition conveyed in their conversation to bring this late-to-the-party reader up to speed on some of the plot underpinnings that had been laid out in the previous books.

As the heart of all creation, the mythical Impossible City has been unreachable — as of yet. Only the minor lunar deities have a limited form of access when they take turns sailing over the city every night, and they have taken that sacred duty seriously.

But alchemists across the globe are vying ruthlessly to breach the walls of the Impossible City in order to acquire dominance over all creation, and one of their ploys involves finding a way to exploit the lunar deities’ nightly mission as a way of getting inside.

This has put the Lunars at risk, and “Tidal Creatures” begins with the untimely death of a Lunar.

The action in these 400-plus pages is set in 24 hours, just before the total solar eclipse across North America in 2017. The chapters in “Tidal Creatures” are named, evocatively, after different seas of the moon.

The succession of events is liberally sprinkled with divine sparkles, diligent sleuthing, and suspense.

Whenever the Alchemists get involved, they seem to bring gruesome ingredients to the mix. On the other hand, an incarnated Doctrine of Ethos provides a more cerebral touch — with a dash of comedy.

McGuire’s construction of an everyday world that has elements of fantasy abiding alongside it is meticulous.

The author also exerts a deft touch in demonstrating that the deities’ concerns resonate with issues the reader will recognize as real-world problems of avarice and over-reach today.

Breathing life into, and significantly upgrading, a host of old mythologies, “Tidal Creatures” is a thoroughly engrossing story.

This week’s book

This week’s book

“Tidal Creatures” by Seanan McGuire

Macmillan — 464 pp — $29.99