The man carrying a huge box full of books to sell commits a series of comic gyrations with his hips to get through the door and staggers about four feet into the bookstore before looking around. His eyes grow wide, and he has the appearance of someone wondering if he's just bumbled into an overly elaborate prank. Meekly, the man asks, "The last time I was here, it was a different store, wasn't it?"

Debbie Sarow, the owner of Mercer Street Books, assures him that he hasn't gone crazy; up till last year, this space was the Queen Anne branch of Twice Sold Tales. Mercer Street Books officially opened on July 15, 2009, but Sarow has been slowly changing the look of the place ever since. Except for a few necessary layout elements—the big window at the front of the store, the tall bookshelves scoring the shop with narrow aisles—it's all brand-new, from the purple coat of paint to the bronze bust of JFK keeping watch over everything. The storefront and bookmarks for Mercer Street Books are decorated with a long-legged bird resembling a crane. It's an imaginary bird, Sarow explains, that her friend drew when she was looking for a compelling image to link with the store. "The last thing I wanted," she says, "was a cartoon cat, or a woman with glasses sitting next to a stack of books."

Of course, "brand-new" is a relative term. Sarow is a beloved member of Seattle's used-books community; she's been selling used books since 2000, working for Twice Sold Tales, Wessel & Lieberman, and Oblivion Books. Just about every other bookseller in town admires her ability to put a great bookstore together and make it seem easy: "Put it this way," a used-bookstore owner said to me last week, "in 10 years, Mercer Street Books will still be around. I don't even know if I'll be around in 10 years."

Mercer Street Books already has a solid collection of general-interest used books (in one hour on a recent Saturday, browsers asked for and received Star Wars novelizations, graphic novels, biographies of poets, and science books), and it's improving with every customer who waddles through the door with a ridiculously oversize box. Sarow is still learning about the demographics of her new neighborhood, noting that she has four Roberto Bolaño novels sitting on the shelf now—back on Capitol Hill, she says, they all would have been snatched up in an instant. But that's all part of the plan: "The minute your bookstore opens for the first time," she says, "it begins changing to fit its location."