Downton's Joanne Froggatt to star with Ioan Gruffudd in ITV romantic thriller Liar

She’ll be playing Laura, a smart and dedicated teacher who’s hesitant at returning to the dating scene after recently getting out of a relationship. Then she meets Andrew – a surgeon played by Ioan Gruffudd (yes, Mr Fantastic from 2005’s Fantastic Four) – whose son is a pupil at Laura’s school, and the two agree to a date. And they both live happily ever after.

Just kidding. The synopsis says that neither realises the “far-reaching consequences” of their relationship for themselves or their families. To add to the mystery, ITV promise the thriller will “examine both sides of a relationship and both sides of the truth”. We’re guessing “who is the liar?” is going to be the key question of the show.

Liar looks like it’s got a solid team behind it: two episodes will be directed by Sam Donovan (Humans, Utopia) and the show was created and written by BAFTA- and Golden Globe-nominated producers and screenwriters Harry and Jack Williams, the guys behind The Missing and One of Us.

Harry and Jack Williams said: “This story deals with highly emotional and important subject matter, exploring modern issues of gender politics through the lens of a character-driven emotional thriller.”

Filming of Liar will begin in London and Kent in November.