Survivors (1975)

S1E1 The Fourth Horseman

A deadly flu is sweeping across the nation at an alarming rate. Abby Grant (Carolyn Seymour) and her husband David (Peter Bowles) know that the virus has already taken millions of lives in China, but they remain convinced it won't reach England. When Abby falls ill and is confined to her bed, Jenny Richards (Lucy Fleming) discovers from a doctor that this is more than just a flu — countless people are perishing. Heeding his warning, she escapes from London to the countryside. Days later, Abby awakens, filled with dread that she might be the last survivor.