Customizable virtual realities and shape-shifting physical ones form the backdrops for Alex Shakar's dense, darkly humorous and thought-provoking second novel, "Luminarium" (Soho Press, 432 pp., $25).

Shakar's story focuses on New York City technology developer Fred Brounian, who's broke, lonely after splitting with his fianceé and moving in with his parents and preoccupied with life's big questions: What is truth? What is reality? What's life for, anyway?

He is spiritually adrift, in need of a rejuvenating jolt that will help him connect more deeply with the world around him in post-9/11 New York.

He's also stressed about his cancer-stricken twin brother, best friend and business partner, George, who has slipped into a coma at the hospital.

With the aid of an alluring researcher named Mira Egghart, Fred undergoes an experimental therapeutic treatment using a helmet with wires sticking out of it that sends electromagnetic impulses through his brain, enabling him to merge with everything in his immediate path, allowing him to enjoy "peak experiences" and "perceive a porous, expanded, possibly even limitless self."

Heavy stuff. But Shakar ("The Savage Girl") successfully maintains a buoyant and bemused tone.

Fred's personal situation parallels his professional life. He, George and his other brother, Sam, are building an Internet experience that allows users to create avatars — cyber-identities — and dwell in tailor-made, utopian virtual worlds where there is no want, need or suffering. A "Postmaterial life," is how George once described it.

They've been preparing for such a project all their lives. The men's father is a traveling magician. As boys, they used to assist in his act, perfecting the art of making fakery appear real. Virtual reality, at its most detailed and convincing, possesses its own magic.

The helmet makes Fred supernaturally sensitive to the people and things around him, inducing a flickering hyper-consciousness. It's almost like the intuitive bond he and his twin, George, had growing up.

But are the images burning bright in Fred's mind since starting the treatment real, or a trick of the imagination?

In the space of a month Fred goes from "seeing God as a dream, to seeing the world as a dream, to glimpsing that he himself might be a dream." His quest for an awakening via technology becomes obsessive. It seems as if his world instead will collapse in on itself.

With big philosophical issues about the nature of existence, a meditation on post-9/11 America, questions about technology, faith and mysticism, corporate intrigue involving the takeover of the Brounians' company, mysterious text messages and the ups and downs (mostly downs) of Fred's peculiar life, there's a lot going on in "Luminarium," almost too much. It could be that Shakar is deliberately trying to shake loose the reader's bearings, too.

As Shakar suggests in the book, maybe the whole universe is one big computer game and we are all bit players plotting a course through the multiple parallel realities this adventure-seeking void generates.

It's a fascinating idea on which to hinge this worthy novel.

Tyrone Beason: 206-464-2251 or tbeason@seattletimes.com