Jennifer Saunders (Absolutely Fabulous), Geoff McGivern (Peep Show), and Bryony Hannah (Call The Midwife) are just a few of the cast set to join Sharon Horgan in Dead Boss, a brand new six-part comedy with a little murder mystery thrown in, for BBC Three.

Written by Sharon Horgan and Holly Walsh, Dead Boss stars Sharon as Helen Stephens, a woman who has never done anything wrong apart from the time she was stopped for drink driving (she thought Sangria was Spanish for Fanta).

So when Helen finds herself falsely imprisoned for murdering her boss she is sure that it is only a matter of time before this horrible mistake is sorted and she is back to her old life. However, everyone else around Helen seems to be conspiring to keep her on the inside for one reason or another…

Against a backdrop of life in Broadmarsh Prison, Helen fights to prove her innocence by finding her boss’s real killer. Whoever it is, he or she is still on the loose and could kill again. Helen documents her time in prison in letters to Maurice, her pen-pal on Death Row in Kansas.

Jennifer Saunders stars as Margaret, the governor of Broadmarsh Prison, who believes that appeals are an irritation and a waste of valuable resources. Geoff McGivern plays Tony, Helen’s hapless lawyer, a specialist in “injury at work” claims, who thinks shouting “You can’t handle the truth” amounts to a convincing defence. Bryony Hannah plays Christine, Helen’s arsonist cellmate who just wants a hug.

Aisling Bea (Come Fly With Me) plays Helen’s self-obsessed younger sister Laura, who is quite happy Helen’s inside as she’s moved into her flat and taken her job. Amanda Lawrence (Above Suspicion) plays Mary, Helen’s nemesis from her former work place, the head office of Entirely Tiles, and Edward Hogg (Misfits, Silent Witness) plays Henry, the weirdo from work who is more than a little obsessed with Helen and realises that his weekly prison visits are the only guaranteed way to spend time with her.

Tom Goodman-Hill (Ideal) stars as Tim and Ricky Champ (Him & Her) as Frank, prison guards and Margaret’s henchmen; Lizzie Roper (This Is Jinsy) plays Top Dog, the big cheese among the Broadmarsh prisoners; Emma Pierson (Hotel Babylon) plays Mrs Bridges, the glamorous and not so grieving widow of Helen’s murdered boss; and Barnaby Kay (Public Enemies) plays Justin, Helen’s absent fiancé, who despite being her alibi, prefers Helen being in prison because he just can’t face dumping her.

The series also features further guest stars in individual episodes to be announced later.

Sharon Horgan and Holly Walsh, said: “We’re thrilled to see our show, which we’ve spent the last decade and a half writing, coming to life with such a ridiculously talented cast and under the direction of a visionary like Steve Bendelack.”