Our tale is narrated by a young woman named Podkayne, christened quite obviously to us—and also within a context she explicitly acknowledges—after the famous Heinlein heroine. Her narrative voice and character resemble those of her literary namesake to a large degree—bubbly, positive, vibrant, sexy, but perhaps more grounded and self-aware—but everything else about Podkayne's milieu is different.

We first see her in action on a dismal Earth, as a military representative of the Martian government. Earth has been shattered environmentally, economically and culturally by an astronomical collision event, and Podkayne is recruiting top immigrants to a healthier Mars. She has lots to say about Terran culture, little of it complimentary. But before her stint is over, she's hailed back to her home planet for a family crisis. And after that, she gets a new assignment. Podkayne is going to join the USO.

Oh, it's called Music, Arts and Drama Division, Martian Navy—MADDMN, or Madams and Madmen—but it's essentially the same. Podkayne's exceptional singing voice has earned her a berth touring the solar system to entertain the troops, starting on Europa, moon of Jupiter. On that satellite she encounters many new friends and experiences, but perhaps none more intriguing than listening to the living, "singing" mountains there.

Europa, it seems, harbors a strange kind of life or quasi-life, contained within the translucent, miles-high prominences that jut up from the frozen surface like giant jellybeans. These structures exert a strange fascination for Podkayne, and she is perhaps on the point of understanding them better than anyone when all hell breaks loose and her life is dramatically diverted.

For without warning the mountains move, and their movements potentially spell curtains for humanity.

Old-time themes made up-to-the-minute

Give John Varley credit for boldness. Each volume in this series has opened up new vistas in a cascade of quantum leaps. The first story was almost a simple Tom Swiftian adventure tale. The second escalated to world-wrecking and interplanetary war. Now this latest entry opens outward beyond the confines of our home star, proving no exception to the steady advancement of scope. By the book's end, we are in exciting cosmic territory that's entirely unforeshadowed on page one. (Whether a fourth book will appear is unknown to me, but the climax of this one seems to allow for such an event.) But our story this time does take a bit of an ambling start to make its leap, and that's where any longueurs will hit the reader.

The first half of the book consists essentially of these things: backstory, very moderately and cleverly inserted; the establishment of Podkayne's persona; and a travelogue of the solar system. Really, there's hardly any "plot" to speak of, aside from sitting on Podkayne's shoulder and observing her daily routines. Now, granted, serving in the Martian navy and touring Europa is not working at Wal-Mart, and there's plenty of visual and SF wonder here, but it's all of the curiously old-fashioned kind of SF where the future was introduced in guidebook manner.

Old-fashioned is a relevant issue where Podkayne's persona is concerned, as well. Although a creature of her era, she also has a Heinleinian personality—as how could she not, in such a calculated homage?—that renders some of her views and pronouncements a tad retro. But you can forgive Podkayne knowing Big Band tunes intimately for two reasons: Her culture has accelerated so fast from our present that such things have not yet receded deeply into the dustbin of history, and Varley also endows her with plenty of more futuristic bits and attitudes. But be warned that if the original Podkayne, lovable as she was, ever grated on you, this one will too.

In any case, after the halfway mark of the story, Varley makes up for any early slowness by tossing about half a dozen shocking monkey wrenches into the mix, and the book accelerates to a melancholy yet exuberant climax.

While not as revolutionary as the Eight Worlds sequence that made his reputation, this book and its predecessors form a true love letter to the genre, while at the same time boosting SF's core accomplishment up a few steps on the staircase to the stars first carpentered by Heinlein and his generation.