In Sullivan’s fantasy novel, deities and the reincarnated band together to prevent the world from being dismantled.

Madog Morfryn, hiding from dark forces called the Niente, gets a message to his children: Twin wizards Merlin and Ganieda are to act as guardians of the legendary Round Table—a “map of the Golden Age”— and protectors of magical children. Many years later, the shifting of the ages is imminent. For the Niente, it’s a chance to destroy everyone, including gods and goddesses, and erase all of history. But Lady Gaea (also called Mother Earth), ensconced in the realm of Elysium, can guide others to reach the harmonious “New Time,” which should be achievable once the Planetary Earth Star has activated. This plan involves multiple individuals, places, and eras. For starters, magical healers, including Ganieda and characters named Nina and Abigail, gather at a healing garden in 21st century London. Long ago, Nina had apparently lived as Nimue, who for a time was Merlin’s lover; numerous other characters are seemingly also reincarnated versions of mythological beings (like Apollo) but aren’t necessarily aware of who they had once been. (Some come from the Welsh island of Mona in the first century.) The narrative follows an assortment of people traversing different realms to track down and/or reunite with particular individuals, all while solving riddles. These riddles range from traditional puzzlers like “How do a goddess and a knight meet?” to broader challenges, as when Nina is told to “crack the curse” of her grandmother, who’s in an “Otherworld.”

Although Sullivan’s novel is part of a series, it reads like a standalone story. There’s no question that the author knows this material, which mingles Greek and Celtic mythologies, thoroughly. This expertise generates a bevy of characters and subplots—perhaps too many; it’s not always clear how certain people connected to the Planetary Earth Star activation are actually helping. Most of the male characters are thinly-developed, from the surprisingly feeble Lord of the Underworld to Merlin, who makes relatively few appearances and, for most of the book, doesn’t even have his iconic staff. The female characters, on the other hand, are striking, such as Nina’s mother, Diana, as well as her Aunt Daphne, both of whom are essential to securing Earth’s bright future, and Delphyne, a horse-sized dragon in Elysium who’s just as accommodating and insightful as Lady Gaea. The author’s descriptions are concise but make an impact: One realm boasts an ocean “so blue that sea and sky seemed to blend into one aquatic world.” Along with a handful of gods and goddesses, the story delivers elves, faeries, and instances of magic. The villains’ side isn’t quite as fruitful; despite clear warnings (“Beware of the Niente,” an oracle cautions), the bad guys make very little impact. (At one point, Ganieda posits that one of the Niente is merely an angry mother who threatens to call the police.) Future entries in the series can productively focus on any of the characters found here, as previous series installments have done.

This myth-fusing, realm-hopping adventure entertains, even if the story and cast aren’t always cohesive.

An American teen discovers her connection to Celtic myth and Arthurian legend in this YA fantasy adventure, the third installment in the Legends of the Grail series.

Seventeen-year-old Nina Liber lives in Manhattan with her mother, Diana, an expert in Celtic mythology. Before their flight to Britain for the summer, Nina dreams of a woman in green who calls her a “Mage” and tells her, “remember who you are.” Diana’s husband, Felix, has been deceased two years, and she’s eager to see her twin brother, Blaise. Nina is skeptical about enjoying sights like Stonehenge and being away from her boyfriend, Owen Pelleas. Once in Hampstead, England, Nina befriends Daphne, her uncle’s occasional flame. Daphne recommends the girl visit Ganieda, a local healer named after Merlin’s sister, to gain peace of mind. Ganieda outlines the relationships between the mythical huntress Diana; her lover, the Roman god Bacchus; and their daughter, Nimue. When she hears of Nina’s dream, she echoes the woman in green by saying, “Mage, it’s time you remember who you are.” Later, a limo takes Nina to a country home called Imworth, where she meets Morgen, the woman from her dream. She tells Nina, “You were Nimue. Only you can find and awaken Merlin” and restore the balance between light and darkness on Earth. Sullivan might have written a fantasy in which her lead throws punches while hunting for relics. Instead, she’s more faithful to Merlin’s complex mythology than to the genre’s tropes. Readers will be reminded of the ways Romans used Christianity to subdue the Druids, who had their own belief system. And while Nimue and Merlin’s romance is intense—they kissed like “a tsunami crashing onto shore”—it’s just a portion of their lives, not the entirety. After seeing her previous incarnations, Nina comes to realize she’s “the power of the universe operating as a point in time and space” and that it might be possible to usher in Satya Yuga, the Golden Age, by reconnecting with the natural world. Lovely black-and-white illustrations by Crow duCray enliven the journey. A glossary is included.

This exuberant fantasy calls on readers to conceive of a loving, balanced world.