Filming is now underway in Scotland, with Jonsson playing lead character Fitzwilliam.
Fitzwilliams is convinced he has to find the killer before they strike again.
Fifth Season has international sales.
(Clockwise from L): Sinead Matthews, Penelope Wilton, David Jonsson, Morfydd Clark, Tom Riley; Tamzin Outhwaite, Matthew Baynton, Mark Bonnar, Nimra Bucha, Douglas Henshall, Jon Pointing, Phoebe LicorishJoe Quigg; Guy Coombs; Pal Hansen; Matt Holyoak; Lee Malone; Bina Khan; Dan Pick; Ellie Harrison; YellowBellyPhoto
ITV Studios-ownedMammoth Screenis producing withAgatha Christie Limited.
Karen Kelly is producing and the casting directors are Karen Lindsay-Stewart and Emily Jacobs.
It is so exciting to see this group of actors embark on the re-telling of this great story.
