Spurred by his wife’s Alzheimer’s diagnosis and disenchanted with the slow progress in finding a cure, a rich Swiss businessman launches a contest for promising young neuroscientists who can think “outside the box.” Chosen for their scientific excellence and originality, they must travel throughout Europe in search of the answers to five fiendishly difficult riddles, each combining an enigmatic neuroscientific question with a geographical and historical challenge. As their personal stories unfold, the competitors share their moments of elation and disappointment when they solve a riddle or reach a dead end. Soon a conspiracy materializes to threaten and endanger the scientists, which at first seems random, but then becomes increasingly deliberate and targeted. The nature of the riddles and the talents of the competitors open a world of discovery for us too as we learn about some of the most pressing areas in current brain research, such as neurodegenerative diseases, stem cell grafts, artificial intelligence, drug addiction, genetics, and the mechanisms of memory. And as the candidates visit some of the great European cities—Prague, Vienna, Cordoba, Cambridge, Geneva, Venice—we also experience their beauty and intrigue.