‘Blimey, fish from space have never been so buxom.’ This is probably the best Doctor Who has ever looked. The location work in Croatia is superb; the monster design – giant crayfish things – is convincingly glistening; the costumes are beautiful. Helen McCrory and Lucian Msamati are great. Only the finale, as the Doctor scales a bell tower to disperse the storm-clouds over Venice, looks like it’s stretching the budget. This could pass as a prestige streaming series.

It’s a shame this, like Venice itself, is built on muddy foundations. The script hangs together, but no more. The aliens disguised as humans is lifted straight from School Reunion, as is the prestigious school backdrop with the monsters feeding on the pupils. Even some of the themes feel cut and pasted – School Reunion had the companion’s boyfriend feeling inadequate in the presence of the sexy new Doctor, this has the companion’s boyfriend feeling inadequate in the presence of the sexy new Doctor. Oh, and Guido blows himself up to destroy the Saturnynes, just like K9.

For me, though, the biggest problem isn’t Toby Whithouse revisiting his old script, but the failure of the script to build any sense of momentum. There’s a lot of wandering back round Venice, and no real mystery to solve. As time passes, Rory gets to have a comedy fight with Francesco, which is amusing but inconsequential. The only scene that really sizzles is the Doctor’s face-off with Rosanna, largely due to Helen McCrory’s performance which pirouettes between coy and cold.

On the other hand, all this just means the episode doesn’t live up to its potential. What we get worked well enough in School Reunion to make this an entertaining sequel, packed with some good comedy (mostly revolving around Rory, with Arthur Darvill proving to be a perfect hangdog foil for Amy and the Doctor), and intriguing hints of the wider ongoing storyline: ‘There were cracks. Some were tiny. Some were as big as the sky. Through some we saw worlds and people, and through others we saw silence and the end of all things.’

Next Time: Amy’s Choice