The Generation That Got Stuck in Lockdown: The millennials in Andrew Martin’s new novel, Down Time, are treading water: caught between youth and age, breaking up, and settling down. >... In Martin’s new novel, *Down Time,* that force has finally arrived. The four friends at its center—Cassandra, Malcolm, Antonia, and Aaron—are a decade or so removed from Martin’s youngest characters, closer to midlife than their bygone adolescence. But that’s not to say the book suggests maturity always correlates with age. The core cast may be older this time around, but they still feel like iterations of the same basic Martin type—self-aware self-saboteurs with a taste for mild sexual humiliation—and the book’s opening chapters feature some of his preferred narrative beats: a relapse, a risky kiss, a friends-with-benefits fling that turns sour. This repetition is sort of the point.…