Frankenstein by Mary Shelley (1818). Mary Shelley's novel was conceived on the shores of Lake Geneva during the famous "year without a summer" of 1816, when she and Percy Shelley spent a stormy June at the Villa Diodati with Lord Byron and John Polidori. The party amused themselves by writing ghost stories; Mary's was Frankenstein. The novel's opening Arctic scenes are bracketed by a closing chapter on the lake itself, with Geneva and the surrounding Alps as the backdrop for the monster's encounters with Victor Frankenstein. Read it before walking the Promenade de la Treille.
The Education of Henry Adams by Henry Adams (1907). A brilliant, melancholy memoir by the American historian, including substantial sections on Geneva at the high tide of late 19th-century Calvinist confidence — diplomats, scholars, and Geneva's role in international affairs through Adams's friendships there.
Calvin: A Biography by Bruce Gordon (2009). The standard modern biography of John Calvin, the city's defining historical figure. Gordon is even-handed about Calvin's grim aspects and gives a thorough sense of the political and religious tensions of mid-16th-century Geneva. Useful background for any visit to the cathedral, the Reformation Wall, or the historic old town.
The Beauty of Humanity Movement by Camilla Gibb (2010). Not a Geneva book per se, but a fine novel by a Geneva-born Canadian writer that captures the international city's diaspora sensibility.