When an anonymous madman threatens the citizens of Toronto with a deadly toxic gas, Murdoch must race against the clock to stop him.



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Episode cast overview, first billed only:
Dr. Julia Ogden (as Hélène Joy)
David Huband ...
Mayor Clarkson
Dr. Sanjay Prasad
Russell Bowes
Tess Degenstein ...
Mary Knowles
Clark Devins ...
Riley Flynn


Det. Murdoch is surprised to be called into a meeting with Chief Constable Giles and the mayor of Toronto. They've received a film from someone apparently gassing his dog. The city has also received a demand for $100,000 - or the entire city will be gassed. Using some of the evidence found in the film, Murdoch is able to locate the site where the extortionist killed the dog and the police find evidence of a very powerful poison having been used. They think they've solved the problem when they find and dismantle a gas bomb but Murdoch determines that the extortionist likely has sufficient gas to create many such bombs. They decide to evacuate the city - and only then does Murdoch realize they have it all wrong. Written by garykmcd

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Crime | Drama | Mystery





Release Date:

11 February 2013 (Canada)  »

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Did You Know?


The doom cloud is far more real than some of the devices used for the show. Mixing household ammonia with household bleach does create a toxic gas that can do lasting harm to people using these common household cleaners in combination, especially in enclosed spaces. See more »


Julia mentions that the ransom note was written using "Baskerville font" which she said is very common. It is common but it is highly improbable that it would be ever used for a mechanical typewriter. Baskerville font is proportional (i.e., every character has different width) so it is not useful for the typewriter, especially the old mechanical one from the beginning of the twentieth century. Typewriter characters has to have the same width each, so non-proportional fonts (like famous Courier) are more likely to be used for them. See more »


Detective William Murdoch: [reading threatening note left by criminal] My cloud of doom comes with advice: one hundred thousand is my price. A lack of funds will seal my plan: today, a mongrel; tomorrow, man.
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References Indiana Jones and the Temple of Doom (1984) See more »

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User Reviews

A dog killer must be stopped from becoming a people killer
11 December 2016 | by (Wales) – See all my reviews

Murdoch is summoned to see the Mayor and Chief Constable Giles. The mayor has received a film of a man killing a dog with poison gas, accompanied by a demand for a ransom of $10,000 not to release the gas Toronto. The mayor is hoping it us a prank, but Murdoch thinks the film appears genuine, and the use of toxic gas is certainly feasible. This isn't what the mayor wanted to hear, especially as CC Giles takes the threat seriously.

The investigation starts with tracing the street boy who delivered the film. He is quickly found, but can't help with the description of the criminal, on account of being blind. Constables Crabtree and Higgins are tasked with examining the film for any clues. Meanwhile, Inspector Brackenreid draws Murdoch's attention to a newspaper story about a murderess called Mary Knowles, who is due to be hanged the next day in the nearby women's prison, and comments that the world is changing, getting crazier, what with women being hanged and cities threatened with poison gas. Murdoch visits noted chemist, Dr Sanjay Prasad, to learn from him if poison gas could be a viable weapon of mass destruction. Dr Prasad says gases are more deadly in confined spaces, so if this film is genuine, the fact that it works outdoors would mean it's a most terrible weapon.

Back in Police Station 4, the Constables have not been able to find anything in the film, apart from a long shadow cast across the ground and up a wall. However, once Murdoch identifies what is making the shadow, he deduces where the film was shot, and visits the site with Crabtree. They find a scene of devastation, with dead rats lying all round, and plants dead and devoid of colour. Murdoch brings Dr Prasad to the site, where they observe that plants have been destroyed even at 100 feet from the point where the gas was released in the film. As to what the agent was, there are several candidates, so the appliance of science is necessary. Dr Grace dissects one of the gassed rats, and finds that its lungs had ruptured, confirming what Dr Prasad had said about the potency of the gas. It is, he thinks, a mixture of other gases, but to find out what the components are, Murdoch needs to test something else that the criminal left at ground zero, a glove. From his examination, he proposes one of the precursors may be sodium hypochlorite, commonly found in bleach. He and Dr Prasad are just trying to work out what could combine with that to produce toxic gas when Murdoch is again summoned to the mayor's office.

Another note has been delivered, specifying how the money is to be paid, otherwise Cabbagetown will be gassed. Murdoch reports the devastation at ground zero. CC Giles wants to make evacuation plans. Inspector Brackenreid advises the mayor not to pay, to avoid encouraging others with malice in mind. Dr Prasad asks the blind street boy if he smelt anything unusual from the man. He did, something sweet like rotting fruit. Dr Prasad realises chlorine or something derived from it is probably the toxic gas, and that can be made from bleach and ammonia. Murdoch traces a huge delivery of ammonia to an empty warehouse where there is evidence of chemicals being made up, together with timing devices.

Mayor Clarkson tells Murdoch that the city will pay, but that he wants Murdoch to do all he can to catch the criminal. Murdoch makes arrangements for the ransom drop, including appointing various Constables in plain clothes to observe the pickup discreetly, but the money is not taken. Instead, Murdoch receives a phone call, giving him eight hours to raise a million dollars. Mayor Clarkson and CC Giles are outraged, the former because it is impossible to raise the money in the time, and the latter because he assumes Police Station 4 bungled the handover. Worse, the mayor voices the suspicion that someone in the Police may be working with the criminal, severely annoying Inspector Brackenreid. Murdoch, on the other hand, suggests that the criminal knows it is impossible to pay, and then the others realise that the criminal intends to go through with the gas release. Then a canister and its attached timer are found, having been left unattended in a public place with the clock ticking.

So, can the ticking canister be prevented from releasing it's cloud of doom? If the city must be cleared, will there be enough time to do it? Who is behind this dastardly scheme, and how can s/he be prevented from doing this wherever else s/he pleases? Can the perpetrator really have so little conscience that s/he would kill potentially thousands of innocent people?

This episode is spot on, with a good mystery that requires real science to make progress, as well as the inspirational and open-minded Detective Murdoch. It makes a pleasant change from a murder to an extortion plot. There are one or two quibbles about the scientific dialogue, but the principles are there, even if the precision is not. Overall, highly recommended.

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