Episode Description: Beware, spoilers! To read - hover over the text.
Gerald Leiden - the head of a large Corporation hires Holmes. Case is very unusual, as Gerald claimed that someone intentional provoked a mutation in the DNA that led to dementia. At first Sherlock didn't believe that this is possible, but Natasha is a scientist involved in the mutations was killed, so she knew something. He also talked to eminent scientists and found that it is possible. The disease Leiden was favorable to his children, and they bought this technology from the former head of Natasha.