Citadel: Diana, the spin-off series, premiered on October 10, 2024 on Prime Video. If you are asking in March 2026, the series has already completed its run. All episodes are available to stream on Amazon Prime Video.
Citadel: Diana is an Italian-language prequel spin-off that explores the origin story of Diana Cavalieri (played by Matilda De Angelis), one of the central characters from the main Citadel series. It serves as a bridge between the original Citadel and the broader Citadel universe that the creators (the Russo Brothers) are building across multiple shows and films.
What you should know: If you have not watched the original Citadel yet, you can start with either the main series or Diana first — Diana works as a standalone but has deeper resonance if you understand the main storyline. The Russo Brothers are planning additional Citadel spin-offs for different markets and time periods.
Pro tip: Check Prime Video directly for your region (Canada) to confirm which Citadel projects are currently available in your area, as international release patterns vary.