Sport Relief special. As you'd expect, there are a few changes to watch out for, including having Sport Relief celebrities walk up those famous stairs to accompany the cash-hungry entrepreneurs in their bid for investment.

To kick off the episode, funnyman Patrick Kielty lends his support to an improbable-sounding invention - the Sideways bike. Two sisters from Southampton hope the Dragons will see the potential in their bottom-toning prototype, ably demonstrated by Ruby Wax. Olympic champion James Cracknell lends a hand to young businessman Liam O'Reilly and his dancing troupe; and Greg Rusedski leaves his tennis racket behind to help two Irish entrepreneurs pitch their portable sports stadium aimed at kids. Jason Manford and Iwan Thomas both have to stand in front of the Dragons and respectively pitch a spectacle-stabilising attachment for sports caps, and a sat nav for skiers.

Before entering the Den, the Dragons and entrepreneurs have all agreed that some of the profits from any investment will go towards Sport Relief. But when it comes down to business, the same rules apply; it's the Dragons' own money and only the very best ideas will succeed. In this tough arena, facing some of the best minds in the business, will any of these hopeful entrepreneurs convince the fearsome financiers that they should walk away with their cash?

Plus, the Dragons visit the Kibera slum in Kenya to find out how the money raised by Sport Relief is helping those in need.