'I've never lost an informant. I'm not starting now.' These words uttered by Paddy Considine's counter-terrorism officer Gabe are meant to sound reassuring but are loaded with doubts, regrets and paranoia. As the tense climax of episode two, it's also the first time that Raza (Nabhaan Rizwan) hears the word 'informant' and now fully understands the risk to his own life and that of his family's as he prepares for a spell of gathering information that may have no end-date.

Considine is perfect as Gabe, deploying just the right measures of rage and empathy within a conflicted individual who has a secret undercover history which has altered his state forever. None of which he can talk about, especially not to his new partner, Holly (Bel Powley) a curiosity-filled Saga Norén-esque cop who is a permanently unsmiling concoction of fixed concentration and naïve befuddlement. In what passes for therapy sessions in his unit, Gabe prefers to discuss early memories of pancakes sticking to the kitchen ceiling.

There are also pancakes being prepared in Raza's household with his mum (Sunetra Sarker) activating the smoke alarms with her efforts. Raza's own alarm bells are set off by the unexpected presence in his home of Dadir (Roger Jean Nsengiyuma), something of an unlikely kingpin in his East London borough and the individual Raza has been assigned to track. Like Gabe, Dadir is also a psychological cocktail: one moment he's a jack-the-lad messing around in A&E or ruining a pompous art student's sculpture, the next he's a brooding 'hand grenade', as Raza describes him, whose brother has just been found dead, the victim of any number of candidates from Albanian gangsters to a cell of white extremists.

All this action happens a year earlier from the beginning of the story, which is based around an official enquiry into the counter-terrorist unit's failure to prevent a deadly attack on a coffee shop. We are left to endlessly speculate on how it went wrong, and who the perpetrator is. With the furore over Bodyguard's one-dimensional use of Asian characters, Informer feels like a stark antidote as we are allowed into the domestic settings and get a sense of the motivations behind a diverse set of characters. And as an incisive exploration into the deeds that we do and their long-term effects on ourselves and others around us, it's a compelling and addictive portrait.

Episodes watched: One and two of six.

Informer starts on BBC One from Tue 16 Oct, 9pm