The first episode of Trinny & Susannah Undress the Nation tackles the theme of breasts and bras in Britain where Trinny and Susannah state "British boobs need help!". Trinny and Susannah aim to investigate why many British women wear the wrong size bra and aim to promote wearing the correct size bra, and emphasize the benefits.
In the second installment of the series, Trinny and Susannah investiage the fashion issues of men, and ultimately aim to get a nation of well-dressed British men.
The third episode features Trinny and Susannah exploring the theme of shape, where they promote wearing clothes suitable to body shape rather than clothing size.
During the fourth episode Trinny and Susannah investigate the theme of age. They aim to encourage the older generation to reclaim the high street and become more comfortable with shopping.
For the last of series one, uniform is investigated by Trinny and Susannah where the duo want to promote wearing fashionable uniforms to work. They set out to prove that uniforms can improve morale and make a workforce feel better about themselves.