Invisible Things

Readers unfamiliar with Davidson's The Explosionist (2008), in which she introduced Scottish teenager Sophie Hunter, the orphaned daughter of two physicists killed in 1923 in an explosion in Alfred Nobel's munitions factory, may flounder in this continuation of Sophie's story. Set in 1938 Copenhagen, in Niels Bohr's Institute for Theoretical Physics, this ambitious sequel is also fantasy disguised as historical fiction. Davidson aptly conveys the excitement of scientific research in the late 1930s, but many may find it challenging to wade through the plethora of scientific theory and historical background and feel invested in Sophie's pursuit, suspenseful though it is, of her family history (which involves Nobel himself). The language is often dense, with cumbersome, information-heavy sentences that develop neither plot nor character; the buildup of the romance between Sophie and her impulsive Danish sweetheart, Mikael, is frustratingly laid-back. The climactic Part Three turns decidedly into fantasy as Sophie travels north by reindeer-drawn sleigh to the ice castle of a foreboding Snow Queen, in a journey reminiscent of Lyra's in Philip Pullman's The Golden Compass, and—somewhat unconvincingly—finds personal freedom at last. Ages 14–up. (Dec.)