Donald James

9 December 1969 (epguides.com) or 29 October 1969 (IMDb)

10^th October, Stepney in London in England

At the Belman-Parsons chemical plant, a management type arrives for a typical day’s work. He asks what happened yesterday because he was off sick. His colleague doesn’t know – he was off sick too. They check the records – every single employee was off sick yesterday except the secretary, Miss Royce. She however hasn’t appeared today.

The police investigate and find that everyone living around the plant thought it was a perfectly normal day – the plant was fully staffed and apparently quite normal.

A normal day at the plant – workforce unknown!

The staff were all poisoned by a mild dose of arsenic. Except one man – the model employee who wouldn’t let a stomach ache keep him away. He drowned. Eventually.

The chemical plant makes cough medicine and other commonplace products. There are no secret projects, there is no special equipment and no reason to hijack the plant for the day.

Why is Miss Royce so keen that her fiancé becomes boss of a power station? It’s not even an especially nice power station. It’s a couple of grand extra each year and a better pension. Hardly worth killing people over.

"Where to locate Jason?" asks Stewart. Sir Curtis thought he was with him but Stewart says the jungles of Bogotá are hardly the sort of place you’d find Jason King. Cut to Jason hacking his way through a jungle, seven minutes into the episode.

But hilariously it is just a photoshoot.

Caroline Blakiston plays Miss Mortimer (aka Miss Royce) – probably better known as rebel leader Mon Mothma in Return of the Jedi.

There is a brief appearance by John Horsley as a detective. Horsley is best known as Doc Morrissey in the Fall and Rise of Reginald Perrin.

Eric Lander played Mr Stayte – the gullible high flier in the power station business. He had a very full twenty year career but seemed to vanish in the mid-70s. His longest run was 140 episodes of something called "No Hiding Place".

Annabelle quite literally gets the rubbish jobs in Department S.

She and Stewart stake out a suspicious warehouse. "Stay here" he says as she foolishly thinks she’ll be allowed to leave the car.

She hears the sound of fighting and does nothing but hold her hands to her face in a "Gosh" motion. Later, when all is quiet, she tries to sneak in but is captured before she even reaches the door. I suppose bright yellow didn’t really help in the unobtrusive stakes.

She is taken to the beauty parlour. Presumably Miss Mortimer (or Miss Royce) is going to manicure her into submission.

She uses all her cunning to talk Leslie Schofield into letting her go. She convinces him that he’s been abandoned by his colleagues and left to take the wrap. Who knew she could act so well?

Jason’s eye is turned by the ladies in the beauty parlour and by his photographic co-star. But there is little more than a bit of leg on show.

Jason smells an expensive perfume on the elusive Miss Royce’s correspondence. He traces it to an exclusive beauty salon and takes the opportunity to have his nails done. Not really but you believed me.

During a later search of the beauty salon, Stewart gives Jason a bar of "face lift" cream. "Thanks a lot" replies Jason, not even tucking the much needed cream in his pocket. He certainly used something before getting his own spin-off series.

After two unrelated tankers drive past in a couple of minutes Jason adopts a thinking face. He says he’s looking for that one moment in the jigsaw when all the pieces come together. Sadly, he doesn’t think to turn the car round and follow the two coincidental chemical lorries.

Jason is being photographed to promote the new Mark Caine novel, "An Amazon for Me". Rather prophetically, they have build a life-sized model of the Amazon rain forest for the occasion.

Jason isn’t pleased – his books have sold perfectly well before without resorting to such sensationalist tactics. Then his co-star turns up and he puffs his chest out with rather more enthusiasm from then on.

Miss Mortimer is a fan of Jason King. He claims he needs her advice for a scene where Mark Caine visits a beauty parlour and she is misty-eyed with awestruck gratitude.

Jason mentions an unpublished novel in which Mark Caine was unable to solve the case and called in the police. He might’ve been joking. Or not.

Sir Curtis is sitting alone in a sleeper carriage, perched rather awkwardly on the edge of his bed. One bump and Sir will be on the floor.

Then Stewart arrives in brown coat, brown hat and brown trousers and it is business as usual.

He later surpasses himself in a small way by wearing a brown tie with little brown spots on it. It’s so adorable.

The teaser is excellent - its the sort of thing Department S should've had more often. We're presented with something which makes absolutely no sense what so ever and yet has to have happened for a reason. The detective work is adequate, helped along by some chunks of luck, and it all flows from beginning to middle to end. They even get the science right. Definitely one of the keepers.