Kevin McCloud meets Rosa and her partner Craig who are turning a century-old, family-owned, decommissioned steam railway reservoir into a home. Their radical plan to reinvent the reservoir into a unique living space involves punching huge holes through the walls to allow light to flood in, a mezzanine with views across the valley and a concrete extension with four bedrooms. Along the way they encounter a pandemic, numerous money crises, pregnancy and a schedule that grows from 12 months to over three years, is it worth it for Rosa to have the reservoir home she has dreamt of since childhood?