Two rival companies are vying to supply Demeter City's energy supply, Fusion Power and Solar Tech. Fusion Power has protests against their bid, but Solar Tech's depends upon a highly valuable crystal to channel and send the solar energy, and there are thieves out to get it. Meanwhile, murder victims start to appear with a two-pronged mark on their temples, and death by cranial trauma.
The officers begin to suspect working girl Sylvain. She 'steals' Haldane's mind using a mind probe (the cause of the previous deaths, it can store up to five minds). Meanwhile, a demonstration of the Solar Tech orbiting solar panel craft goes wrong, and the power beam starts to burn its way through Demeter City.
If you've seen heist movies like Entrapment, and giant ray beams slicing through the World (in a host of 60s shows and of course James Bond movie Moonraker) you've seen this before. It's very well done, entertainingly packaged, with the always reliable Tom Chadbon as the smarmy, supercilious, and corrupt Fusion boss, with some nice special effects. Sadly, Sheila Ruskin, a normally fine actress, is too constrained here, perhaps because it sounds like she's been dubbed with a East European accent by another voice artist (actually, this occurs often in this show, normally Americanised accents).
What really lifts this show from the mere entertaining to essential viewing is one piece of inspired casting. The drop dead gorgeous Alison Fielding plays the call girl thief Sylvain. Normally playing posh totty (she has a beautiful speaking voice), here she's either putting on a mid-Atlantic accent or is dubbed. But she's costumed and made-up immaculately, not quite an obvious call girl (except when she picks up her marks at the bar), more an expensive escort. She only made a handful of screen roles, all in the 90s, which is where I first came across her, and this is one of them. Her most memorable performance is in the Inspector Wexford mystery Simisola. She is damn hot, but also very pretty, and you can easily see why and how she'd lure her marks to get what she wants in the end. If for no other reason, I'll always have a soft spot for this episode.