Knowing me, knowing you

For four young friends, the summer of 1983 will never be forgotten. A blissful spell of rebellion, love and freedom - to a soundtrack of Abba. But nothing lasts forever. Three decades on and librarian Maggie is facing chemotherapy for breast cancer, alone. When she hears that ABBA are reforming for one gig in Stockholm, she resolves to contact her old friends to travel together to the concert - just as they promised they would all those years ago. But it's not as simple as it seems.