Watson and the fellows investigate the perplexing case of a family man with a bullet lodged in his head who insists he is a Scottish soldier and seems to be hiding something nefarious; Watson looks for clues to whom his estranged wife Mary is dating.

When Sasha discovers a link between her current patient, who has advanced cancers and distinctive lesions on his tongue indicative of Cowden syndrome, and a cadaver she dissected during medical school, the team traces the case to Amish country.