Early into Chimamanda Ngozi Adichie’s new novel, narrator Chiamaka, or “Chia,” muses on the two women who matter most to her. There is her best friend, “organized, buttoned-up, ambitious” Zikora, a successful lawyer who has been less fortunate in marriage. There is her cousin Omelogor, a former banker, who is bracingly forthright and ruthlessly single-minded. Then there is Chia herself, a travel writer with nowhere to travel to during lockdown, who spends her days ruminating on everything from absent friends to lost lovers to the way her life has panned out. “But what is the final measure for making the most of life,” she asks herself, “and how would I know if I have?”