Informer centers on Raza (Rizwan), a young, second generation Pakistani man from East London who is coerced by Gabe (Considine), a Counter-Terrorism officer, to go undercover. Gabe, who has a past he is unwilling to expose, is joined by Holly (Powley), his ambitious and endlessly curious partner. As the investigation heats up, the stakes for all three get higher and higher.

This series is a spin-off from the long running BBC medical drama "Casualty". Set in the same hospital as its sister series, this show follows the everyday lives, professional and personal, of the doctors, nurses and patients who find themselves, for various reasons, in the wards of Holby City General Hospital.

There are four mutually interfering narrative strands in The Singing Detective. First is the hospital-ward story, described by Potter as a "sitcom", which owes a certain debt to an earlier play, Emergency-Ward 9 (itself a satirical reaction to the popular hospital soap opera of that time, Emergency-Ward 10, which Potter had watched while hospitalised, like his protagonist Philip Marlow, with a flareup of psoriatic arthropathy). Second is the detective story being created mentally by the protagonist, Philip Marlow, as he lies helpless in his hospital bed. The third strand consists of flashbacks to Marlow's childhood in the Forest of Dean, and the traumatic experience of witnessing his mother's infidelity one day in the woods, combined with guilt over her later suicide in London. The fourth strand concerns Philip's ex-wife, Nicola, whom he imagines is conspiring with a shady film producer to bilk him out of film rights to his novel.