The Third Day was created by Felix Barrett (founder of immersive theatre company Punchdrunk) and writer Dennis Kelly for HBO and Sky Atlantic.

The series is structured in three interconnected parts: 'Summer' directed by Marc Munden, 'Autumn' as a live event, and 'Winter' directed by Philippa Lowthorpe.

The middle part, 'Autumn', was broadcast as a 12-hour live immersive theatre event filmed on the island, intended to let audiences 'inhabit the story as it happens'.

'Autumn' featured Jude Law alongside other cast members plus a special appearance by singer Florence Welch.

Katherine Waterston, Paddy Considine and Emily Watson joined the cast in July 2019, followed by Naomie Harris and John Dagleish in August.

Filming took place from July 2019 in Essex and Kent, England, with the fictional setting of Osea Island and its causeway; numerous real locations were used including Dungeness Fog Signal Station, Hever Castle, Chislehurst Caves and Shellness Beach on the Isle of Sheppey.

The series' original May 2020 premiere was postponed after HBO and Sky pulled it from the schedule because post-production was disrupted by the COVID-19 pandemic, delaying release to September 2020.

The first episodes of both 'Summer' and 'Winter' premiered at the 2020 Toronto International Film Festival before the show's official broadcast.