Lord Sugar turns the candidates' attentions towards the highly profitable keep fit industry. The teams have two days to devise and brand a new fitness class that reflects recent popular trends like Zumba or Body Pump, which attract gym members to classes in big numbers. They must then pitch their routines to leading health and fitness chains, who will pay for the rights to run them if they like what they see.

Sixteen candidates begin their fight for one-life changing opportunity - a quarter of a million pounds to start up a business with Lord Sugar as their partner. In the first task, the boys compete against the girls. Each team must buy blank goods, add value by printing a design onto them and then sell them from stalls on the streets of London. It is a test of the candidates' creativity, marketing and salesmanship.

Lord Sugar calls the teams to the Victoria and Albert Museum. Their task is to invent a new household gadget, create a prototype and pitch for orders to some of the country's biggest retailers.

Lord Sugar decides to mix up the teams for the third task, which is to come up with a new condiment; one team goes for a Mediterranean-style ketchup, and the other a chilli chutney. Half of each team head to a condiment factory in Essex to make their product while the others stay in London to design brands and set up sales appointments.

Lord Sugar asks the teams to set up second-hand shops in London's fashionable East End, home to a thriving market in retro and refurbished household goods. The teams must source second-hand stock from auctions, junk shops and car boot sales, and resell at a profit during a one-day-sale from their respective shops.

It is week six, and Lord Sugar sends the candidates to Scotland, where they must make gourmet grub and sell it on the streets of Edinburgh. The teams decide on Italian meatballs and Scottish stew, but before heading north there is a spot of market research at one of London's fancy street food fairs. It is clear from what is served up that there is more to this business than dishing up a burger and chips.

The teams are called to a warehouse in Essex; Lord Sugar tells the candidates that this is how he started out, buying wholesale goods and selling them on for a profit. Both teams are given 150 pounds to spend on products of their choice, with Essex as their selling ground. Products are purchased and hopes for big profits are pinned on a collection of mops, MP3 players, fake tan and false eyelashes.

The eighth task starts with an early morning trip to Waterloo Station, but the teams are not going anywhere; underneath the railway arches is a big screen with a message from Lord Sugar. He tells the teams to take a look around; they are surrounded by graffiti, and this is what they will be selling next. The teams have one day to meet and convince up-and-coming urban artists that they are the right team to represent them in a one-off gallery sale.

The longest champagne bar in Europe at St Pancras International is the venue chosen by Lord Sugar to launch the latest task. But he is not buying the teams bubbly; he is setting them the challenge of raising awareness of English sparkling wine, which rivals champagne in quality, but not in market dominance. It is a real issue for the industry - can the teams devise a brand and identity for the British product to compete with cava, prosecco and champagne? Their marketing campaigns will be judged on merit by discerning wine industry experts.

The candidates are called to meet Lord Sugar on a rooftop overlooking the City of London, where countless financial deals are done on a daily basis. For one day only, the teams will be representing an online daily deals website that offers Londoners exclusive deals in hotel stays, beauty treatments, posh dinners and premium products. It is a test in the teams' negotiation skills; they must strike the right deal, get a good discount and deliver their offers to the website by 7pm that evening. Nick and Karren watch on as the teams get increasingly desperate in their attempts to secure quality deals at the right price. Businesses are bemused as candidates try to negotiate offers on everything from candles and teeth whitening to five-star meals and fish pedicures.

The candidates give their assessment of their personal triumphs and failures and the lessons they have learned during the process. Not to mention the bitching, backstabbing and the blame games they have had to overcome to get this far. The programme investigates the five contenders' family backgrounds and reveals more of their characters as friends and family talk about the childhood, upbringing and personality traits that have shaped the final five into who they are today. Nick Hewer and Karren Brady share their thoughts on the candidates' performance thus far and assess the strengths and weaknesses of each individual, explaining what qualities they believe Lord Sugar sees in the final five.

Lord Sugar calls the teams to Burlington Arcade, a luxury shopping centre in London's West End. He spells out that in the current economic climate Britain still has a taste for the finer things in life, but they should come with an affordable price tag. He reveals that the candidates' latest task is to consider affordable luxury retail markets and come up with a new product range.

They knew they had to impress Britain's toughest boss. If they failed, they'd get the chop. 16 hopefuls went into battle for Lord Sugar's £250,000 investment. Now, he explains how some candidates lost the plot completely and others survived by the skin of their teeth.

The final episode of this series sees Lord Sugar name his business partner. The final four candidates are called to the Institute of Directors in the City, where Lord Sugar asks them to pitch their business concepts to him right there on the spot. Then it is down to business with Margaret Mountford, Mike Soutar, Matthew Riley and tough-talking Claude Littner.