Each game begins with four participants (referred to by the host as "the usual suspects") who are sequestered in a soundproof booth backstage.

One of the four is chosen at random to play the game onstage as a contestant, while the others remain in the booth, unable to see or hear the proceedings until the host calls on them.

After all six answers are locked in, the booth is turned on and the suspects give their individual opinions of how many responses are correct, but not specifically which ones.

The contestant leaves the show, as does the helper (if applicable), and enough new suspects are introduced in the next game to bring the pool back up to four.

However, after 26 episodes had been filmed, reports surfaced of some onstage contestants being able to see a video screen (intended to be hidden from their view) that displayed the correct answers.

Since these contestants could have used this screen as an unfair advantage, these 26 episodes were scrapped and re-filmed at 12 Yard Productions' expense.

In the episode broadcast on 1 February 2013, a contestant called Sharon achieved imperfection in the first round, answering 0 correctly and allowing the usual suspects to win automatically.

In the final, none of the usual suspects chose to come down and Sharon won the prize fund, achieving perfection and winning £1,000.

Since this rule was introduced, six contestants – Ann, Emma, Phil, Beth, Sarah and Tracy – have played all of their eight games.