Mrs. Dokes was an unseen villainess mentioned in Castle's fifth season opener, "After the Storm" (airdate September 24, 2012). She was the mother of Lamar Dokes and his unnamed younger sister; the former being a friend of future Senator (and the series' main antagonist) William H. Bracken.
During his encounter with Kate Beckett (after Beckett found out about Bracken being the mastermind behind the murder of her mother, Johanna), Bracken mentioned Lamar and how they were friends when Bracken was 14, stating that he would help Lamar with his homework after school. The Dokes family went through tough times after Mrs. Dokes suddenly lost her job and was facing eviction from her home, and in response to her situation, Mrs. Dokes turned heel by orchestrating a double-murder/suicide.
The psychotic villainess laced her children's hot chocolate with crushed up pills, with both Lamar and his sister fatally succumbing to the poisoning. After killing her children and leaving a note that revealed her financial struggles, the evil Mrs. Dokes committed suicide by hanging herself.