Two teams take on a guessing game with a series of unusual, unlikely and often unbelievable line-ups. The celebrity teams have to work out who in each line up has the odd skill, talent or secret. The teams are allowed to ask questions to the lineup, to determine which of the number of available choices is the Odd One In. In the first series, playing along are a section of the audience who have keypads to record their results, after the penultimate lineup the top scoring audience member is chosen to compete for a cash prize if they can spot the final Odd One In with the help of the two teams and the audience. For the second series the audience no longer has the keypads or play for the cash prize. The final round is replaced with the Familiar Faces round where a member of each of the previous rounds return for one last Odd One In.