‘Haunted Harmony Mysteries: Key to the Castle’ Cast Guide: Who Stars In The New Addition To Hallmark’s Ghostly Mystery Franchise?
We’re headed back to Ireland tonight!
Haunted Harmony Mysteries: Key to the Castle, the third installment in the network’s Haunted Harmony Mysteries franchise, reunites fans of the cozy, supernatural mystery with music teacher Gethsemane Brown (Tamera Mowry-Housley), who is introduced to the world of ghosts after moving into a haunted Irish home in 2023’s Haunted Harmony Mysteries: Murder in G Major.
Last year welcomed a sequel, Haunted Harmony Mysteries: Buried at C. But tonight’s Key to the Castle sees the quaint Irish town rocked by a ghost hunter show. However, according to the network’s synopsis, “it’s up to Gethsemane and Eamon (Risteárd Cooper) to solve the unexpected murder of the host, allowing the brand-new spirit to cross-over.”
Fans of Haunted Harmony Mysteries are no stranger to Mowry-Housley and some of her other Key to the Castle co-stars, who have now worked on all three films in the Haunted Harmony Mysteries series. But some faces may be… might we say… a mystery?
Puns aside, Haunted Harmony Mysteries: Key to the Castle premieres tonight at 8 p.m. ET/PT on Hallmark Channel, with next-day streaming on Hallmark+. Check out who’s who in Haunted Harmony Mysteries: Key to the Castle below.
Light spoilers ahead for Haunted Harmony Mysteries: Key to the Castle ahead!
Photo: Hallmark Media
Tamera Mowry-Housley returns as Gethsemane Brown, a music teacher hailing from Virginia who moves to Ireland to work at a prep school. However, her travels don’t just lead her to professional purpose, but also to the world of the supernatural after she meets Eamon McCarthy, the late composer who owned her house before her.
Mowry-Housley has become one of Hallmark’s frequent leading ladies, most recently starring alongside fellow network mainstays Fiona Gubelmann, Yan-Kay Crystal Lowe, and Melissa Peterman in All’s Fair in Love and Mahjong. Her career began early, with her breakout role on the sitcom Sister, Sister with her twin sister, Tia Mowry.
Photo: Hallmark Media
Eamon McCarthy (Risteárd Cooper) is a ghost, who in his past life, was an Irish composer. He owned the home that Gethsemane moved into in Haunted Harmony Mysteries: Murder in G Major, and has been a sort of “spirit guide” to her since they met in the 2023 film.
Cooper, an Irish actor and comedian, appeared on the British miniseries Quiz, in addition to the Acorn TV Original miniseries Acceptable Risk.
Adam Fergus as Inspector O’Reilly
Photo: Hallmark Media
Inspector O’Reilly (played by Adam Fergus) is a police detective, who in his interest in Gethsemane, also seeks out her assistance with honing his musical skills in order to impress his family. Fergus also reprises his role from Haunted Harmony Mysteries after appearing in the first two films of the franchise.
He has earned TV credits on shows like Being Erica, Supernatural, and Clean Sweep outside of Hallmark Channel.
Photo: Hallmark Media
Marco Grazzini plays Griff Kennedy, a calculus teacher and a colleague of Gethsemane’s whose interest in her is quite apparent. Grazzini has appeared in all three Haunted Harmony Mysteries movies, rounding out the love triangle between him, Gethsemane, and Inspector O’Reilly.
Outside of Hallmark, Grazzini stars as Mike Valenzuela on Netflix‘s Virgin River, and also lent his voice to the role of Alejandro in Cartoon Network‘s Total Drama Island.
Photo: Hallmark Media
Ciara Gordon (Sarah Gallagher) is a member of the ghost show being filmed in the castle. She cites Gethsemane’s story as a significant reason why her team headed to Ireland to film Before and Afterlife, what she called “more of a docuseries” than a reality show about haunted happenings.
This marks Gallagher’s first Haunted Harmony Mysteries movie. She has appeared in shows such as Shortland Street, Trivia, and Peaky Blinders.
Photo: Hallmark Media
In addition to losing his wife, Ed James (played by Aidan Redmond) also had his role taken away from him on Before and Afterlife.
Redmond has appeared in films like 79 Parts and Son of the South, and has also made a cameo on Daredevil.
Fianna Nolan as Eliza
Photo: Hallmark Media
Eliza (Fianna Nolan) is the cinematographer on Before and Afterlife, and has become a protege of Kent, who she really admires. Nolan appeared in Haunted Harmony Mysteries: Buried at C, though in another role as Shannon. She also made an appearance in a 2025 episode of Anne Rice’s Mayfair Witches.
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