The series is based on CJ Skuse's 2017 novel, which was optioned by See-Saw Films back in 2017, with Sky Atlantic joining the project in 2019 and Kirstie Swain adapting the book into a six-part series announced in 2020.

Ella Purnell was cast in the lead role in November 2023 and also serves as an executive producer on the series.

For the second series, Tamsin Greig, Rish Shah, Taj Atwal, and Jenny Walser joined the cast, announced in August 2025.

Filming for the first series took place in Southend-on-Sea in November and December 2023, using locations such as Southend Observation Tower on Pier Hill, the Western Esplanade's Cliff Lift, and the Adventure Island theme park.

Some scenes were also filmed near the River Colne in Oxhey Park, Watford, and filming for the second season began in August 2025.

The title sequence, created by London-based Peter Anderson Studio, was designed to visually explore the lead character's psychological state using brutalist painting aesthetics, neon-lit rain-soaked streets, and a bespoke hand-drawn typeface with sharp extensions to create an ominous mood.

The title sequence won a BAFTA in the 'TV Craft / Titles & Graphic Identity' category in 2025.

The series score was composed by Isobel Waller-Bridge, and the theme song 'Do You See Me Now' was written and performed by Isobel Waller-Bridge and Chinchilla; the soundtrack also features tracks from Billie Eilish, Icona Pop (ft. Charli XCX), Labi Siffre, and the Spice Girls.