|'The Deadly Air'
by Lester Powell
After the testing of a vaccine goes horribly wrong, Steed and Doctor Keel investigate, and discover that Heneger, one of the scientists involved, is attempting to sabotage the project. But while interrogating the suspect, they learn that another scientist called Doctor Craxton is really behind the plan. Craxton locks Steed in a room booby-trapped with a vial of lethal virus. Keel believes that Steed is infected, but then learns that Truscott, the project director, replaced the vials of virus with vials of water by as a security precaution. The security guards arrest Craxton.
Ian Hendry (Doctor David Keel), Patrick Macnee (John Steed), Ann Bell (Barbara Anthony), Michael Hawkins (Doctor Philip Karswood), Keith Anderson (Heneager), Richard Butler (Herbert Truscott), John Stratton (Doctor Hugh Chalk), John Stratton (Doctor Owen Craxton), Douglas Muir (One-Ten), Ingrid Hafner (Carol Wilson), Cyril Renison (Doctor Harvey), Anthony Cundell (Ken Armstrong), Geoffrey Bayldon (Professor Kilbride)
Directed by John Knight
Produced by Leonard White
UK: 16th December, 1961
*Featuring Doctor David Keel and John Steed
*This episode no longer exists