Doctor Who: Boom Review - 9 Ups & 3 Downs

It's been clear this season that Ncuti Gatwa and Millie Gibson have fantastic chemistry both on and off screen, and this episode puts it front and centre. For the last two weeks, we've had some very frenetic stories that haven't really slowed down for a moment and let these two interact in a meaningful way, but here, they're given plenty to do on a character level.

Ruby is thrown in at the deep end for the first time, having to do much of the heavy lifting on the Doctor's behalf – both physically with regards to having to venture away on her own, but also emotionally, trying to keep the Doctor's anxiety in check. She excels at the latter, keeping him focused and also overriding his decisions at the risk of her own safety. Ruby in prior stories seems to be a little too casual with her world being turned upside-down, but here, that level-headedness and no-nonsense approach seems like an intentional character strength.

Seeing the two holding each other up, and relying on each other – it seems like they're going for a more even-footed Doctor/companion dynamic this time around, though this feels more akin to Twelve and Clara than it does Thirteen and The Fam, which, let's be honest, is probably for the best.