Episode 8

A rock star's baby is taken during a party, and MI5 is pulled into a world it usually only watches from a distance. Riff, played by Andy Serkis, is a popular icon whose private life has suddenly become a national security matter. And the party is loud, glamorous, and exactly the wrong place for a baby to disappear. The case drags the team through the flashbulb glare of fame, where nobody's account of anything is reliable and everyone is worried about image. For MI5 the case is unusual: the victim's family has lawyers and publicists before it has anything else. For the public it's sensation; for MI5 it's a kidnapping with all the usual pressure and none of the usual anonymity.

Fiona goes undercover to get closer to the couple, against Adam's wishes. She goes anyway, and the episode lets the two of them argue it out between the meetings. That disobedience is its own small war inside the larger one, and it runs through the whole episode. The case gives the team something they rarely get: a victim the whole country cares about. Adrian Lukis's John Sylvester, Vincenzo Nicoli's Rudolphino Ponti and Rebecca Palmer's B give the celebrity world its supporting cast. Tim McInnerny's Oliver Mace hovers at the edges, because even a kidnapping can't happen without the committee taking an interest. Shauna Macdonald's Sam, Rory MacGregor's Colin, David Oyelowo's Danny and Rupert Penry-Jones's Adam make up the team. Peter Firth is Harry. Howard Brenton and David Wolstencroft wrote it; Bill Anderson directed.

The odd thing about this one is how well the private tragedy and the public circus sit together. Serkis gives Riff a proper character, not a caricature, which helps the whole episode. The baby is what matters, and everything else is noise. The baby's safety stays the centre of gravity, whatever the circus throws up. The episode has the good sense to keep coming back to that, even while the cameras flash and the handlers spin. It's a solid middle-of-series hour with more heart than most.