The Avengers.S06E19.The Curious Case of the Countless Clues

In a spoof of Sherlock Holmes, Sir Arthur Doyle (Peter Jones) – equipped with pipe, cape and deerstalker hat – is investigating a seemingly careless criminal, who leaves masses of clues wherever he goes ... but no one can solve the crimes, not even Steed, because all the clues are fakes: left behind by a blackmailer, who is planting them to incriminate wealthy men, as part of a sophisticated extortion racket.
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Teleplay by Philip Levene
Directed by Don Sharp
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Guest Starring: Anthony Bate, Kenneth Cope, Tony Selby, Peter Jones, Tracy Reed, Edward de Souza, George A. Cooper, Reginald Jessup