‘So that’s what I sound like.’ The simmering story arc of Series Eight starts to come clearly into view, as Clara takes the lead in what’s practically a “Doctor lite” episode. With Capaldi stuck on the TARDIS set like Tom Baker in Part Three of Logopolis, Coleman gets to take charge, posing as a Doctor, mustering the survivors of the Flatland invaders and turning the aliens’ powers against them – all while fending off her boyfriend’s concerned/controlling (YMMV) phone calls. After passing the “terrible choice” test in Kill the Moon, she’s now auditioning for the main role. The Doctor seems to have mixed feelings: she makes a mighty fine Doctor, but goodness has nothing to do with it. Missy seems happier with the outcome.

After the fairytale of the Matt Smith years, the Capaldi years are leaning into Hinchcliffe horror. The opening is typical Hinchcliffe: a man falls victim to something awful, before the TARDIS even arrives. What follows is exceedingly (if tastefully) grisly: a female police officer reduced to a diagram of her own nervous system; human beings are flattened into 2D, then reconstituted as painful, shuffling simulacrums straight out of an A-Ha video. The deaths are horrible; the aesthetic is stark and cold – a windswept railway sidings; a graffiti-plastered subway; a decrepit warehouse. In nine episodes the show has forged a new style, one rooted in grim rather than Grimm reality.

I wonder if it was a sequencing error to place this Jamie Mathieson script immediately after his Mummy on the Orient Express. The comparison doesn’t work in Flatline’s favour – both have a similarly inexorable and unknowable enemy hunting its prey (and a sympathetic pseudo-companion in Perkins/Rigsy), but while Mummy is built around the mystery of its monster, Flatline’s creatures – despite some attempts to question their motives – are straightforwardly nasty. As a result, despite their clever MO and some generally excellent effects (Capaldi peering out of the TARDIS never looks anything but a CSO insert), this tends to very mildly drag as it plays out as a long chase sequence. The pay off, ‘I name you the Boneless’ is rubbish against the Doctor’s last-moment reveal of the Mummy’s secret. The end result has enough cleverness that it works, but never engaged me like the Mummy episode.

Next Time: In the Forest of the Night