A wild new theory suggests that the acronym CHIS used in Line of Duty may prove that Steve Arnott is 'H'. The sixth series of the BBC One crime drama premiered on Sunday night and saw DS Steve Arnott ( Martin Compston ) begin to look into the enigmatic DCI Joanne Davidson ( Kelly Macdonald ) and her handling of investigating the murder of journalist Gail Vella.
However, there is an added complication as Joanne's new colleague is a AC-12 veteran, DI Kate Fleming ( Vicky McClure ). Throughout the episode there was such a frequent use of the word CHIS, which is as the BBC announcer confirmed after the episode ended, an acronym for Covert Human Intelligence Source.
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