In 1998, Maverick Records engaged a market-research company to collaborate on a promotional plan for Supposed Former Infatuation Junkie, the highly anticipated sophomore album from Alanis Morissette. “Because of the nature of the business, we knew that Alanis had earned a ‘Free Pass’ from radio and MTV,” the researchers wrote—“her first song would get massive airplay no matter what it was.” After that, they offered several possible fates, including a “doomsday scenario” in which no songs beyond that first single received significant airplay. In this disturbing outcome, they projected three million in sales—a fine yield for a mortal, but disastrous for a superstar whose previous record had sold over thirty million copies.

“Sadly,” the researchers reported, “we were dead on with this projection.” Supposed Former Infatuation Junkie quickly became a consummate example of the sophomore jinx, a slump from which Morissette’s career has yet to recover. When she sings, on one of the album’s underperforming later singles, that whenever she thinks of the early ’90s, an ex-boyfriend’s “face comes up with a vengeance, like it was yesterday,” she seems to be eerily forecasting present attitudes toward herself.

That song, “Unsent,” invites one of the only linear readings on a long and rambling record that is otherwise a mess. After Jagged Little Pill, a taut commercial juggernaut of an international debut, what could account for a follow-up so odd? For starters, its creator had already endured a doomsday scenario of a different sort: Jagged Little Pill’s success had been woozy, steep, and quick; a tour that began at tiny rock venues concluded, eighteen months later, in sold-out stadiums where crowd-control personnel were forced to request that fans “surf the internet, not the Morissette.” This is a lot for a twenty-one-year-old to deal with.

In the wake of this ambush of success, Morissette took two friends and three relatives on a six-week trip to India, with hopes of dealing with events that should have, as she would sing later, delivered her to “a far-gone asylum.” The purpose of her trip was a sequence of soul-based inquiries, and Supposed Former Infatuation Junkie constitutes her own research report.

There are more-obvious ways to organize the findings of the heart, but Morissette favors the inventory, the lawyerly catalog. “Thank U,” that free-pass first single, works entirely in this mode, with a chorus that thanks,...