Brady finds himself drawn to the case of Professor Tanya Brofuri (Zena Marshall), a dissident scientist from a foreign, unfriendly power. Partly this is because he’s angry about the way her freedom has been curtailed, but also because he believes she might be able to help him become visible again …..

The opening of The Locked Room is interesting.  For the first time there’s a voice-over as Brady sets the scene about Tanya (after speaking out at a public meeting she’s been frog-marched back to her embassy).  It’s an obvious way to save time which, given the twenty-five minute format, is quite important and it also helps to thrust us straight into the story with very little preamble.

It’s never explicitly stated, but there’s a strong streak of self-interest in Brady’s actions.  Yes, he’s displeased that a fellow scientist should be treated so badly by her country, but he also wants her help with his continuing experiments to reverse his invisible state.  Had the story been longer then possibly this is a theme that could have been developed, unfortunately the brief duration of the story didn’t really make it possible.

Another undeveloped angle concerns Porter (Noel Coleman), the man from the ministry.  He expressly forbids Brady from rescuing Tanya, but after he does so anyway, there’s no comeback.  Instead,  Porter was happy to arrange American citizenship for her.

Rupert Davies casts an imposing shadow as Dushkin.  It’s never explicitly stated that Dushkin and Tanya are Russian but the implication is obvious enough.  He’s another lightly sketched character, but his threats (first to dispatch Tanya to a sanatorium for an extended stay and then later to send her home in a coffin) are chilling enough.

With Brady being invisible for most of the episode, Zena Marshall has to work hard to convince us that there’s a growing attachment between Tanya and Brady.  But this she does very well and Marshall (probably best known as the treacherous Miss Taro from the first James Bond film, Doctor No) is a pleasing presence throughout the story.

The “twist” is one that the audience should have seen a mile off – everything seems settled, Tanya is due to head off to the airport and Brady, Diane and Sally wave her goodbye as a car comes to pick her up (the invisible Brady represented by a floating hanky!).  But wait!  The car wasn’t sent by the Americans, it came from those pesky Russians (or whoever) and they aren’t kindly disposed towards Tanya.

Brady saves the day of course – the sight of an apparently riderless motorcycle and sidecar is an arresting image – and whilst The Locked Room lacks a great deal of depth, Davies and Marshall help to make it an amiable watch.