In 1997, a few grams of Timothy Leary’s ashes were blasted into orbit aboard a Pegasus rocket. As a metaphor of the grand showman’s spaced-out antics, it was the perfect conclusion. And if Leary’s expanded consciousness is still out there peering down on planet Earth, he must be wondering what took T.C. Boyle so long to write a novel about him.

Leary, the infamous promoter of LSD, the guru whom Richard Nixon once called “the most dangerous man in America,” feels like a character God cooked up in a lab specifically for T.C. Boyle. With a Ph.D. in psychology, Leary first gained notoriety in the early 1960s at Harvard where he made wild claims for the therapeutic and transformative effects of hallucinogens. When the faculty turned against him, Leary began a decadeslong trip — sometimes as a fugitive — that took him in and out of prison.

No fiction writer could compete straight on with that psychedelic life. But for his novel “Outside Looking In,” Boyle wisely keeps to Leary’s early career. And besides, he isn’t interested so much in staring directly at Leary as at the shadow this great burning ball of gas casts on ordinary people caught in its orbit.

The protagonist of “Outside Looking In” is a hard-working young man named Fitz Loney. Despite having a wife and young son, Fitz has quit his job as a high school psychologist to pursue a Ph.D. at Harvard under the tutelage of a “shining star” named Tim Leary. Before he got to Harvard, the riskiest thing Fitz had ever ingested was vodka with orange juice: “He hadn’t come to grad school for God or mysticism or mind expansion or whatever they were calling it,” Boyle writes, “but for a degree that would lead to a job that would pay his bills and get him a house and a car that actually started up when you inserted the key and put your foot down on the gas pedal.”

Such square attitudes make Fitz reluctant to turn on, tune in and drop out, but the politics of graduate school require him to participate. Boyle portrays Leary as a blend of cheerfulness and manipulation, and he’s attentive to the new lingo that Leary and his disciples are slipping into the language — somewhere between science and mysticism — like “the Fifth Freedom, the freedom to explore your own mind.” Sensing Fitz’s hesitancy to jump in, Leary tells him, “It’s hard to let go, hard to evolve, but that’s what we’re doing here, that’s what the project is all about. We’re explorers, right?”

Leary’s “experiments” involve weekly sessions at his house where sympathetic faculty members, sycophantic grad students and various hangers-on come together, drop acid and have mind-blowing sex. Boyle re-creates those sessions in all their supercool flimflammery, along with the haze of legitimacy meant to obscure Leary’s violations of basic medical procedure. “It was research, that was all, only research,” Fitz tells himself. But he’s astute enough to know that what’s happening here has no clinical justification, and we can feel Boyle’s censorious attitude pumping through these pages like a naloxone drip.

That’s not to say that “Outside Looking In” is one long buzzkill, but it is a farce laced with tragedy: the story of a good man’s increasingly tortuous moral gymnastics. “Tim was unorthodox, but that was the whole attraction, wasn’t it?” Fitz asks himself.

There’s plenty of zany comedy here; the humor, though, is tempered by the damage that Leary wreaks on Fitz and his family. Boyle may sympathize with Fitz and his wife as they slide toward oblivion on Leary’s snake oil, but he’s a merciless chronicler of their descent. And all along the edges of “Outside Looking In,” we can see signs of the country growing more alarmed and more enchanted by the promise of a drug-induced nirvana.

This is a superbly paced novel that feels simultaneously suspenseful and inevitable. As Boyle has suggested in the past, “casting off societally imposed strictures” is often a recipe for loneliness at best, abuse at worst. Yes, it’s a drag, man, but any enlightenment that comes from a pill isn’t worth having.