The question that loomed over Adele in her four years between albums was how — or if — she could follow her blockbuster with something equally striking. “There is no beating or redoing ‘21,’” said Ryan Tedder, another producer and songwriting collaborator for both “21” and “25.” “You’re lucky if at one point in your life you stumble across a unicorn in the woods. The odds that you find a second unicorn are extremely remote, and she’s aware of that. I think that ‘25’ will be enormous, regardless of anything. But that wasn’t the goal. She wanted to put out the best thing that was the most honest.”

At this rehearsal, with a journalist in the room, Adele was a musician above all. She moved decisively through new songs and old ones in preparation for TV appearances and a Radio City Music Hall concert (and NBC TV taping) on Tuesday, Nov. 17, three days before the worldwide release of “25” (XL/Columbia). And she sang in full-throated glory, capturing the vengeful bite of past hits like “Rolling in the Deep” and the hushed suspense and pealing chorus of her new one, “Hello.” Her stage arrangements echo her albums; she wants the songs familiar enough for fans to sing along.

Adele had largely maintained public silence while recording “25.” Her reticent re-emergence was a brief, anonymous television advertisement, first shown on Oct. 18 during “The X Factor” in Britain. It was the beginning of “Hello”: just somber piano chords, Adele’s voice and the lyrics — “Hello, it’s me/I was wondering if after all these years you’d like to meet” — with no other information.