David Walliams is joined by stage and TV actress Sheridan Smith, who transforms into a real-life Barbie doll, faces an unlikely dilemma whilst filming a swords-and-sorcery epic and hits all the wrong notes as a cruise ship singer with a chip on her shoulder. David and Sheridan play bickering husband-and-wife contestants on an ill-fated game show called What's She Cross About? and star in a 1970s politically correct film, Carry On up the Sexual Harassment Tribunal.