The elderly war veteran in Dementia is named George Lockhart and he is played by Gene Jones. He lives alone in his secluded house and is struggling with memory loss and other symptoms of Alzheimer's disease. His family, who he has been estranged from for years, decides to intervene and hires a live-in nurse named Michelle, played by Kristina Klebe.
Initially, George is resistant to having a stranger in his home but eventually bonds with Michelle, who seems caring and attentive. However, as time passes, George begins to experience strange hallucinations and nightmares that cause him to question Michelle's true intentions.
It is eventually revealed that Michelle has a dark past and is not who she seems. She has been hired by a mysterious organization to steal something valuable from George's house, but her loyalties are tested as she grows close to him.
Throughout the movie, there are flashbacks to George's time as a soldier in the Vietnam War, giving insight into his character and the trauma he has experienced. The film is a tense and suspenseful thriller that explores themes of memory, aging, and trust.