Those familiar with the previous titles in Garth Nix’s The Keys to the Kingdom series will be expecting another carefully structured, action-filled adventure. They would be half right. In the seventh and final instalment, Lord Sunday, Nix has abandoned his familiar formula. The elements are all there – the seventh key, the seventh Trustee, the seventh fragment of the Will – but the meticulous structure that has been the benchmark of the series is replaced with a mad dash to the ultimate conclusion. As a result, this book reads like a finale to the interrupted climax of book six, Superior Saturday (2008). This lends the narrative a frenetic energy that mirrors the plot, as the ever-encroaching Nothing grows closer to overwhelming the House, the Universe and Everything, while the ‘real world’ (which fans will understand isn’t really the ‘real’ world but only Arthur and Leaf’s version of it) descends into further chaos as a result.