Jeff Rawle, who plays Shaun Dingwall and Doc Martin in Top Boy, will join the cast of Grantchester for the eighth season.
Jemima Rooper (The Girlfriend Experience) and the pair will play as guest actors, though their roles in the ITV show are for the time being unknown.
Robson Green's DI Geordie Keating and Tom Brittney's as Reverend Will Davenport will return in Season eight of the popular crime drama.
Charlotte Ritchie (Bonnie) Tessa Peake-Jones (Mrs C), Kacey Ainsworth (Cathy Keating), Oliver Dimsdale (Daniel Marlowe) and Nick Brimble (Jack Chapman) will reprise their roles.
Will is living in bliss until his world is turned upside down by a terrible accident in his lowest hours. Distress will send him on a dangerous downward spiral.
Meanwhile, Geordie is content with his new relationship with Cathy, but it's not long before their happiness is jeopardized when they both receive shocking news at work.
Green said of his return to the show: "It's so nice to be back on Grantchester. A series that just keeps getting better with age. Everyone involved is at the top of their game, and this extraordinarily charming, likeable, dark, and edgy program is a joy to be a part of."
"I'm just ecstatic that Grantchester is continuing to produce a show I've always loved," Brittney said. "To be a part of a show as well-known as this, which is now in its eighth series, is an absolute pleasure."
Grantchester is available onITV in the United Kingdom, and MASTERPIECE PBS in the United States.