Production Number: 3420 Tape Number: Unknown


Following an act of sabotage at Truscott Research Laboratories, a medical establishment specialising in vaccine production, Steed and Keel are called in. They encounter more disruption but can find no strong clues to the identity of the perpetrator.

In an experiment in the isolation room, one of the chief scientists, Dr Philip Karswood, suffers a life-threatening seizure having been exposed to a strain of the vaccine that is one hundred times the standard intended dose. Steed discovers, with the help of Armstrong, a technician at the facility, that someone has taped a phial of the contaminated vaccine to a ventilation fan serving the isolation room. The phial was placed so it would break when the fan was activated with fatal results. Karswood's life is only saved due to his speedy transfer to the centre's hospital, where he is put in an iron lung.

Steed and Keel decide to stick themselves at the very centre of the action and volunteer to be the next test subjects. However, there are two scientists, Craxton and Heneager, who are intent upon sabotaging the work of the centre. Craxton wants to discredit the vaccine and then develop it himself elsewhere after the fallout has died down, raking in the significant financial rewards and Steed and Keel stand in his way. He plots to remove them, starting with Steed, who he tricks into the isolation room... and the fan spins into action...


Read the full story in Two Against the Underworld

The Avengers: Series 1, Episode 23
Production Completed:
Thu 7 Sep 1961
Recording Format: 405 Line B/W Video
Archive Holding: DOES NOT EXIST
John Cura Tele-Snaps: Photographed
Reconstruction: Made 2010
UNITED KINGDOM: Sat 16 Dec 1961
Never transmitted outside the UK


ABC Midlands: Sat 16 Dec 1961, 10.00pm
ABC North: Sat 16 Dec 1961, 10.00pm
Sat 16 Dec 1961, 10.00pm
ATV London: Sat 16 Dec 1961, 10.000pm
Sat 16 Dec 1961, 10.00pm
Grampian: Sat 16 Dec 1961, 10.00pm
Scottish: Not transmitted
Southern: Sat 16 Dec 1961, 10.00pm
TWW: Sat 16 Dec 1961, 10.00pm
Tyne Tees:
Sat 16 Dec 1961, 10.00pm
Ulster: Sat 16 Dec 1961, 10.00pm
Westward: Sat 16 Dec 1961, 10.00pm
Dr David Keel
John Steed
Carol Wilson
Barbara Anthony
Dr Philip Karswood
Herbert Truscott
Dr Hugh Chalk
Dr Owen Craxton
Dr Harvey
Ken Armstrong
Professor Kilbride
Ian Hendry
Patrick Macnee
Ingrid Hafner
Ann Bell
Michael Hawkins
Keith Anderson
Richard Butler
Allan Cuthbertson
John Stratton
Douglas Muir
Cyril Renison
Anthony Cundell
Geoffrey Bayldon

Not released.


StudioCanal, UK: 'Mission Brief' reconstruction by Alys and Alan Hayes, narrated by Alan Hayes, combining off-screen Tele-Snaps with a newly-written narration Stills Gallery


Writer Lester Powell
Series Theme & Music
Johnny Dankworth
Robert Macgowan
Story Editor
John Bryce / Reed de Rouen
Leonard White
John Knight

Other credits not available

Studio Teddington 2
An ABC Network Production


  • Production Brief... The Deadly Air was one of four Series 1 episodes that were held back due to a planned break in transmission for The Avengers. The intention appears to have been to return with a seventeen week run which would have resulted in a thirty-nine episode series in total. However, only four episodes were 'in the can' before ITV drama production and scheduling were severely disrupted by industrial action called by the actors' union Equity. These four episodes commenced transmission from December 9th 1961 (as announced at the end of the Kill the King broadcast on September 2nd) with Dead of Winter the last Series 1 episode to be recorded airing first, and The Deadly Air following a week later. Despite the long break in transmission, these final four 1961 episodes are not considered a separate series from the first twenty-two episodes.

  • The episode was rehearsed and recorded in Studio 2 at Teddington. Camera rehearsal were held on Wednesday 6th September 1961 from 10.30am until 9.00pm and on Thursday 7th September 1961 from 10.00am until 6.00pm. Recording followed on directly from this second rehearsal session and wrapped at 7.00pm.

  • The Deadly Air was the highest rated episode of Series 1, seen in 5.1 million homes. Amazingly and this is as much an indictment of how badly the series fared in networking (see our Regional Variations sections) it proved to be the ninth most-watched episode of the whole series, 1961-1969.

  • On Location... This episode was entirely studio bound and no location work was undertaken.

  • Trivia... Three of the final four episodes of Series 1 have a definite science fiction flavour to them hi-tech laboratories in The Deadly Air and Dragonsfield, and cryogenics in Dead of Winter heralding the more fantastical direction The Avengers would take in later years.

  • In addition to The Deadly Air, Lester Powell also wrote Mission to Montreal, the introductory adventure for David Keel's replacement, Dr Martin King. Powell is best remembered for creating the fictional detective Philip Odell. The character was the central figure in a series of BBC Radio thrillers which ran from 1947 to 1961, with Robert Beatty taking the role of Odell for the duration of the series. Beatty would go on to play Colonel Ilenko in The New Avengers episode Target!

  • In common with The Radioactive Man earlier in Series 1, which had been adapted by Patrick Brawn from a 1958 Canadian Broadcasting Corporation play, there is an outside chance that The Deadly Air was based on a previous script by Lester Powell entitled Night of the Plague. This play was produced twice first in the USA for NBC under the Kraft Television Theater banner and transmitted on Wednesday 20th March 1957 and then in Canada for CBC as an entry in the General Motors Presents play series, transmitted on Sunday 9th June 1957. Night of the Plague does indeed appear to have contained plot ideas in common with The Deadly Air, though settings and characters are different. Interestingly, the Canadian version featured a little-known actor named Patrick Macnee among the cast and the Head of Drama at CBC at the time was a certain Sydney Newman!

  • There is some possible confusion over the spelling of the name of the technician in this story. Dave Rogers' The Complete Avengers has it as 'Heneger', whereas TV Times magazine bills the character as 'Heneager'. Since the latter is from a contemporary source, we have elected to use that spelling. On a similar note, The Complete Avengers lists Armstrong's first name as 'Keo', but this is almost certainly a typo. TV Times suggests the much more likely 'Ken'.

  • The method by which the vaccine samples are rendered useless is not described in existing synopses, but is shown clearly the Tele-Snaps, which depict a pressure gauge and controls. A sign beside the gauge warns that the pressure in the chamber must not be allowed to drop below 15lbs per square inch.

  • It is made clear in the synopsis in The Complete Avengers that the doctor in the test chamber (Karswood) receives a fatal dose of the disease. The Tele-Snaps, however, show him in an iron lung machine, implying that there is a chance of him recovering. Despite this, his character is not seen in any of the subsequent images. It is likely that the original synopsis was accurate but glossed over the attempts made to nurse Karswood to health. Judging by the later revelation that the rogue sample is one hundred times the strength of the vaccine, Karswood's survival seems highly questionable.

  • And Finally... It would appear that there was at one stage the intention to have a live monkey in the laboratory. Steed and Keel were supposed to administer a dose of the vaccine to the animal, to ascertain whether or not the vaccine was dangerous. This plot element has wormed its way into reference works, presumably from contemporary synopses. However, the Tele-Snaps clearly show Steed and Keel performing this experiment upon a live guinea pig. The production team had worked with a monkey prior to this, in Please Don't Feed the Animals, so perhaps they had a bad experience that time or maybe they simply wanted a bit of zoological variety...

Plotline by Alan Hayes UK Transmissions by Simon Coward, Alan Hayes and John Tomlinson
Declassified by Alan Hayes with Richard McGinlay

With thanks to Dave Matthews, Dave Rogers, Piers Johnson, Mike Noon, Andrew Pixley,
Jaz Wiseman and StudioCanal for their kind assistance


Back to Top