Bridget Lennon, an interior designer for retail stores, visited the shop last week to buy a copy of “Hornet’s Nest” as a Christmas present for her fiancé. “You put down the first one, and you want to read the second; and you put down the second, and you want to read the third,” Ms. Lennon, 27, said. Although she said the $45 price tag was steep, she figured that by the time she, her fiancé, her fiancé’s sister and his father had all read it, “between the three or four of us that we know immediately who want to read it, it will pay off eventually.”

Image Partners & Crime, a mystery bookstore in the West Village, is selling the British edition of the third volume in the Stieg Larsson series. Kizmin Reeves, the shop's co-owner, said she bought them, as anyone can, on Amazon.co.uk. Credit... Richard Perry/The New York Times

Ms. Reeves said she did not understand “how the American publisher got so behind the eight ball on their publishing schedule.”

Paul Bogaards, a spokesman for Knopf, said the company wanted to allow interest to build as more and more readers discovered the first two volumes in the series.

“The sales on Book 1 and Book 2 are so strong that you wouldn’t want to add Book 3 to the mix immediately,” Mr. Bogaards said. According to Nielsen BookScan, which tracks about 70 percent of retail sales, “The Girl with the Dragon Tattoo” has sold 764,000 copies in hardcover and paperback in the United States, and “The Girl Who Played With Fire,” which came out here in July, has sold 199,000 copies in hardcover. That book was the first work in translation to go to No. 1 on The New York Times hardcover fiction best-seller list in 25 years. (The last one was “The Name of the Rose” by Umberto Eco.)

The series, with its highly idiosyncratic protagonists and reportorial detail, has garnered critical praise along with a growing fan base. In a review of “The Girl Who Played with Fire” in The New York Times, Michiko Kakutani wrote that the series worked because “Mr. Larsson’s two central characters, Salander and Blomkvist, transcend their genre and insinuate themselves in the reader’s mind through their oddball individuality, their professional competence and, surprisingly, their emotional vulnerability.”

Knopf’s announced print run for “The Girl Who Kicked the Hornet’s Nest,” scheduled for a May 25 release, is 500,000 copies.