Written by Alan Pattillo
Directed by David Lane

The Square Triangle starts, as many episodes do, with the Moonbase interceptors scrambled to meet an incoming UFO.  But one interesting difference is that the sequence is played out with no music.  Usually Barry Gray’s unmistakable score underpins such action, but not here.  I assume it was a directorial decision and it certainly does give the scene a different feeling.

When Straker learns that the UFO will land in Southern England he orders the interceptors not to attack and to return to base.  Although it’s unfortunate that the stock footage used shows them all returning without their missiles!

Foster leads the mobile units in the hunt for the UFO.  As ever, there’s some first rate modelwork, particularly the glowing UFO in the forest, which is very effective.

Rather less effective is the subplot concerning Cass Fowler (Patrick Power) and Liz Newton (Adrienne Corri).  Together, they’ve hatched a plot to kill Liz’s husband, but their best laid plans go awry when the alien walks through the door instead.  Liz shoots the alien dead.

As Foster put it: “it’s just lucky for her that an alien came through that door instead of her husband.”

Liz and Cass are taken back to SHADO HQ for questioning and Foster is convinced that they intended to murder Liz’s husband.  Straker doesn’t see what they can do, as there’s no actual evidence and he tells Foster that “we are not in the morality business.”  After the amenisa drug is administered, Liz and Cass are sent on their way.

The ending is nicely ambigious as we see Liz visiting a grave that could be her husband’s.  For once, the downbeat closing music doesn’t play out over a shot of the moon, instead it follows Liz as she leaves the church.  Liz is met by Cass and when he appears the music strikes a particularly sinister note, which was a nice edit.

Patrick Mower has never been an actor that I’ve particularly warmed to, so it’s probably his presence that makes this one of the less effective UFO episodes for me.

There are some good points though, such as the moral dilemma that the SHADO team have to deal with  – can they effectively condone a possible murder?  But short of keeping Cass and Liz constantly under surveillance 24 hours a day there’s not much they could have done.   And once the amnesia drug was administered the two of them would have forgotten about everything that had happened anyway, so how could anything have been proved? it’s another insight into Starker’s single-minded SHADO operation.