There’s quite a lengthy recap at the start of this episode (nearly three minutes) which suggests that it was underrunning a little.  Sabotage in Space is a rather static instalment – understandable since most of the action takes place aboard the rocket.

But the enclosed nature of the episode isn’t all bad news as it allows Brown’s discordant presence to slowly become more apparent.  That he’s a fish out of water is evident right from the start – he doesn’t know how to strap himself into his take-off seat, for example – and there are numerous other signs that he’s not the man he claims to be.

Noticing that Geoffrey’s still carrying his book (although as yet nobody knows that he’s the author), he launches into an earnest debate about life on Mars which both Geoffrey and Margaret gently disagree with.  Henderson is more forthright, labelling Brown’s book as “tripe”!

Mary is far from happy.  The man that Brown replaced, Professor Hawkins, should be working with her – but Brown spends all his time glued to the radio.  When Mary complains to Henderson he doesn’t seem to be terribly bothered about her problems.  He tells her to be a good girl, gives her a kiss and saunters off!  Mary then pulls a “ooohhhhh” face which tells us all we need to know.  This may be the space age, but this scene indicates that there’s still some way to go before we see equality between the sexes.

Buchan Island discover that Professor Hawkins isn’t present on the rocket when he turns up at the base.  One point – Hawkins is supposed to be Australian, but neither Horsfall or Coulouris have the trace of an Australian accent.  It might have been fun for both of them to attempt one, but on second thoughts perhaps not.

Ian quickly works out that the imposter is Harcourt Brown, a Mars obsessed fanatic.  But the others on the rocket remain in ignorance since Brown was able to destroy the receiver before Buchan Island could transmit the news.

As for Professor Wedgewood, he’s nowhere to be seen.  A line of dialogue explains that he’s headed off for hospital, but since he’s only got a broken arm you’d have assumed he’d have hung around a little longer to see everything was all right.  But in story terms the Professor is now surplus to requirements and his absence from the rest of the story means that the production saves a little money (that’s one less actor they have to pay).

By the end of this episode the MR4 has reached the Moon’s orbit.  Whilst Brown remains behind, Henderson, Mary, Geoffrey and Margaret rendezvous with the supply rocket which is now in their orbit.  Margaret returns with the new radio, but Brown then closes the hatch and fires up the motors, leaving Henderson, Mary and Geoffrey locked out of the control room.  He reveals his true identity and then tells them all that he’s heading for Mars ….