It initially appearing to be a mini-series about Yorkshire CID Detective Ronald Craven's (Bob Peck), investigation into the murder of his daughter Emma (Joanne Whalley), a young scientist and member of an environmental pressure group.
Soon, however, and before the end of the first of six episodes, Edge Of Darkness begins to essay consistent themes between historical conflicts and the nuclear currencies of the future, developing recurrent themes throughout man's history on a planet that regenerates to ensure its survival, ideas first proposed in Dr. James Lovelock's Gaia theory.
Delve even deeper and Edge Of Darkness becomes layered with subplots examining national intelligence, Northern Irish politics, the secrecy of Government and an ancient rivalry between the Knights Templar and their brethren in the Teutonic Knights.

THE PLOT

One: Compassionate Leave
Two: Into The Shadows
Three: Burden Of Proof
Four: Breakthrough
Five: Northmoor
Six: Fusion

COMPASSIONATE LEAVE
The series opens with Craven investigating corruption and election fixing in a trade union, paying particular attention to the re-election of the union leader, James Godbolt (Jack Watson). With much of the local establishment dissuading him from continuing his investigation, including his own Chief Constable, Craven calls a halt to it, leaving the union hall to pick up his daughter Emma.
On returning home, Emma is shot dead by an unknown assailant who escapes. Rather than mourning her death, Craven prefers to get involved in the investigation into his daughter's murder, beginning with a search through Emma's possessions. There, he finds a pistol and notes on the environmental pressure group she was involved with - the GAIA organisation.
Having exhausted his local contacts, Craven travels to London in the hope of getting closer to the truth behind GAIA and the Northmoor nuclear facility Emma had been investigating before her death.
Darius Jedburgh (Joe Don Baker) and Pendleton (Charles Kay) from the CIA and the Prime Minister's office, respectively, are introduced and are shown to have been involved with Emma. Following a suggestion by Jedburgh, Pendleton makes contact with Craven, offering enough hints that the killer may not have been after him, but Emma.


INTO THE SHADOWS
Investigating further, Craven is led to Emma's boyfriend, Terry Shields (Tim McInnerny), who provides further details on GAIA, of which he is also a member. Immediately after, Craven decides to visit Pendleton who introduces him to Henry Harcourt (Ian McNeice), also attached to the Prime Minister's office but who has been drafted in from the City to investigate procedural and legal irregularities at the Northmoor nuclear facility.
Harcourt and Pendleton, working from here on in as a team, inform Craven of Emma's role in a break-in at Northmoor and that she had recently been exposed to large doses of radiation. They further suggest that Godbolt's involvement in union corruption may have been affected by his relationship with the owners of Northmoor.
Pendleton and Harcourt arrange from Craven to meet Jedburgh who makes available a file containing details on GAIA and the Northmoor facility.
Meanwhile, the Metropolitan Police, as part of their investigation, track down who they believe is the killer and Jerry Grogan (Kenneth Nelson), CEO of Fusion Corporation flies in to meet Robert Bennett (Hugh Frazer) of IIF, Northmoor's current owners regarding a buyout of the facility.