The brain disease Alzheimer's is both fatal and incurable. In order to develop a treatment, the disease must be detected early. Oskar Hansson and his research team at Lund University have discovered that the protein tau which in the disease forms the knot in the brain's nerve cells, leaks out into the blood. A blood test can therefore now diagnose patients early in the course of the disease. The hope is also that it will speed up the development of disease modifying therapies, especially for the early stages of Alzheimer's disease. In the film you meet Oskar Hansson and his patient Alf Andersson.