The DIY SOS team is back and in Birmingham helping a family in need. Charlotte and Chris have twins who were born prematurely and have a condition known as global development delay. It is a condition which has slowed down their progress of walking and talking. Their cramped house is hindering their progress even more, and if they have any chance of catching up, they're going to need DIY SOS and a host of volunteers from the local community to rebuild their lives and give the family a better future.

Nick Knowles travels to Hopesay, Shropshire to meet ex-fireman Joe and his seven-year-old daughter Lucy. Joe lost his wife Jess suddenly in 2014, partway through renovating an old cottage into what they had hoped would be a dream family home. Now work has ground to a halt and Joe and his daughter are living in a tiny caravan in the garden. Having heard of their plight, the DIY SOS team arrives to give them the home Jess had wanted for them, backed up by an army of local tradespeople.

The team are in Cheltenham, Gloucestershire, to help 17-year-old disabled athlete Scott Jones achieve his dream of going to Tokyo 2020.

Rachel and Andy Smith's middle child Isaac has spastic quadriplegia, a severe form of cerebral palsy and Andy or Rachel must be available at all times to care for him because he sleeps fitfully in a hospital bed in the family living room. It's making family life stressful including for Isaac's siblings as the design of their home is in conflict with what this family really need.

Nick Knowles and the team join forces with two world-famous British institutions, Great Ormond Street Hospital for Children and the Royal Horticultural Society's Chelsea Flower Show, to transport Chris Beardshaw's gold medal-winning garden across London, crane it over buildings and rebuild it on the hospital's roof. For hundreds of families, Great Ormond Street Hospital has become a second home. For parents that means being by their child's bedside around the clock, and for children, it results in a constant treadmill of appointments and treatments. When Rosie was just two years old, her heart began to fail. Great Ormond Street Hospital doctors diagnosed her with restrictive cardiomyopathy, an extremely rare condition affecting just one in a million children, where the heart is too weak to pump blood. Rosie has had an operation to fit a mechanical heart while she awaits a donor, and so she needs intensive around-the-clock care with her mother consistently by her side. Maisy has epidermolysis bullosa, known as butterfly syndrome, which is an agonising skin disorder where the body lacks the protein it needs to hold the layers of skin together, making it blistered and as fragile as a butterfly's wing. It is such a rare and serious condition that Great Ormond Street Hospital specialists have been looking after her since birth. Despite the brilliant world-class care, there is nowhere private outside for the families to escape from the constant noise, bustle and bright lights of this huge hospital. The DIY SOS team and Chris Beardshaw have taken on this hugely ambitious build, with tricky logistics and emotional volunteers, in order to offer the many brave families a bespoke and lush calming rooftop garden as a space of welcome respite.

Nick Knowles, Laurence Llewelyn-Bowen and the trusty purple shirts venture north to Blackpool to tackle this year's most ambitious build in DIY SOS: Million Pound Build for BBC Children in Need. This special DIY SOS is set to capture the nation's heart as Nick and the team highlight the plight of the nation's 250,000 young carers who care on a daily basis for their parents. Blackpool Carers Trust provides limited out-of-school respite and training activities as well as peer support for young carers, and their current centre is bursting at the seams. The Blackpool Carers Trust, which is supported with funding from BBC Children in Need, provides much-needed support to young carers like 11-year-old Tyanna and ten-year-old Gracie who bathe and generally care for their ill mother, former nurse Suzanne who was diagnosed with osteoporosis, but also their dad Sean who is dealing with cancer. The Carers Trust has inherited a broken, enormous build which sees a dramatic reinvention of a huge overgrown garden and run-down, neglected building into an unrecognisable, inspiring and colourful base for youths with caring responsibilities. It's all done in the cheeky DIY SOS spirit which includes an attempt on their very own 'most selfies in three minutes' for a Guinness World Record!

Nick Knowles, Laurence Llewellyn-Bowen and hundreds of Worcestershire volunteer builders rescue 17-year-old Antonia Payne-Cheney, who has been kept prisoner in hospital for the last three years by Ehlers-Danlos syndrome, a debilitating and rare condition. Until 14 she was a healthy girl, enjoying gymnastics and cheerleading, but now she is hospital bed-bound. Her joints regularly dislocate and she is unable to eat normally, so she is fed through a line directly into her heart. As a result of her complex condition, Antonia will remain in hospital until the necessary home adaptations have been made. To give Antonia the freedom to return home, the ambitious DIY SOS build features a functional sterile space for medical procedures in her own bespoke bedroom, a specially adapted wet room that offers her freedom and dignity and an accessible space for her to socialise with family and her friends. As ever, it's an immensely challenging build carried out over the hottest week of the year, so sweat and tears flow in this emotional and entertaining episode.

When 36-year-old Terry Guest, father of two daughters, had a catastrophic brain injury, he was left with severe disabilities. As his house was unsuitable for him, the only care available was an old-people's dementia care home, where he remained for several years. In need of more day-to-day care and a place of his own, his sister Tracey stepped in to offer help, but her house was also unsuitable. Now DIY SOS and their team of generous South Yorkshire volunteers and suppliers are stepping in to adapt Tracey's home and also, in a DIY SOS first, build Terry his very own separate pad at the end of the garden. Battling adverse Yorkshire weather, the team's electrician Billy's tricks with the electrics and a massive misjudgement in ordering materials, this unique build definitely tests the team's resolve.

The team help transform the home in Bidford-on-Avon of a woman suffering from mastocytosis, a rare genetic disorder, who has been forced to stay in the living room of her family's house under constant care since her diagnosis at the age of 18. Nick Knowles, Laurence Llewelyn-Bowen and hundreds of Warwickshire volunteer builders redesign the entire house to provide Chloe with independence, creating a self-contained apartment complete with bedroom, wet room and sitting room within her family home.

Nick Knowles, his team and a group of volunteers are in Monmouth, Wales, to transform the family home of Charlotte, a mother recovering from a stroke that left her with brain damage, speech loss and partial paralysis. The current layout of her home makes it difficult for Charlotte to move around and have her physiotherapy treatment, so the team redesign the house to make things easier for her, her husband Rob and their children.