"In the Garden," "Three Sisters Island", The Sign of Seven Trilogy", "Circle Trilogy", "Three Sisters Trilogy", "Key Trilogy" and "The Inn of Boonsboro" are some trilogies by Nora Roberts. Nora Roberts has written over 200 books, which includes several trilogies and series.
The "In the Garden" trilogy is about three women discovering past memories and dangerous secrets against the backdrop of their historic home and a new garden business. The trilogy includes "Blue Dahlia," "Black Rose" and "Red Lily."
The "Three Sisters Island" trilogy is about Nell Channing finding refuge on Three Sisters Island, away from her abusive husband, and starting a new life. The books in the trilogy are "Dance Upon the Air," "Heaven and Earth" and "Face the Fire."
"The Inn of Boonsboro" trilogy is inspired by Nora Robert's own inn and the town that she loves. The trilogy includes "The Next Always," "The Last Boyfriend" and "The Perfect Hope."
"The Sign of Seven" trilogy offers an unexpected and darker side of Robert's writing. This series centers on three men who unwittingly unleashed a demon on their small town when they were boys. The stories document the paranormal activities that plague the town and how the protagonists attempt to save it.