The House of Hades, the newest book in Rick Riordan’s bestselling Heroes of Olympus series, sold almost 350,000 print copies in its first week on sale at outlets that report to Nielsen BookScan. Approximately 249,000 copies were sold through BookScan’s retail and club channel, an increase of 26% over the 198,000 copies that The Mark of Athena sold when it made its debut in 2012. Hades is Riordan’s only hardcover release this year; in previous years he published two hardcovers annually featuring books from his Olympus series plus other series.

According to BookScan, The Mark of Athena sold 237,000 copies in its first week on sale last year, a figure that, unlike the 2013 total for Hades, does not include sales at Walmart. Without Walmart, BookScan reported that Athena sold 39,000 copies in its first week of sales last year through the mass merchandiser channel; with Walmart Hades sold approximately 101,000 copies. But just looking at sales from the retail and club channel, the 26% increase in sales over Athena is an impressive performance for Hades in this age of growing e-book sales.