It depicted investigations handled by enquiry agent Frank Marker (Alfred Burke), an unmarried loner who is in his early forties when the series begins.

The series was created by writers Roger Marshall and Anthony Marriott with the aim of getting away from "square-jawed" heroes of the type featured in Hollywood movies—a wish shared by Alfred Burke, the actor chosen to play Marker.

Many of the narratives conclude with Marker leaving a situation as it was at the beginning of the episode—for example, in "The Man Who Didn't Eat Sweets", he fails to tell his client that she is one of her husband's three wives.

Of the 41 episodes produced by ABC, only five are currently known to exist in television-broadcastable format—the rest being victims of the common television company policy of wiping.

The episode does establish key aspects of Marker's character: his modest lifestyle arising from his modest fees for his work—the oft-quoted "six guineas a day plus expenses" (which became £6.30 a day in the later Thames-produced episodes, once Britain converted to decimal currency)—his shabby office, and the fact that he is often compelled to take on almost any offer of work just to earn his living.

The other surviving series 1 episode, "The Morning Wasn't So Hot", sees Marker cross paths with an organised criminal gang; he is thrown into the River Thames by underworld figures as "persuasion" to drop his enquiries into the whereabouts of a missing girl he has been hired to trace—she has been forced into a life of professional vice at the behest of the gang.

The ABC episodes ended with "Cross That Palm When We Come To It" (broadcast on 13 April 1968) as Marker acts for a solicitor over some stolen jewels, as a go-between with the gang who stole them and want the reward money.

Commonly referred to as 'the Brighton series', the collection of seven episodes links together to tell the story of Marker's release from prison and his gradual rehabilitation into everyday life, culminating in him renting a new office and starting up again as an enquiry agent.

In the first half of the episode, Marker is released from prison and heads for Brighton where the parole system has arranged accommodation for him with a Mrs Mortimer (Pauline Delaney).

Through an extensive location-shot sequence on the sea front at Brighton, the viewer experiences Marker's disorientation at a world which appears to have changed considerably since he was sent to prison.

Although completely innocent of any wrongdoing (as he points out, he would be stupid to steal the money as it would immediately end his parole and send him back to prison) Marker is placed under immense pressure by Kendrick's other employees once they find out he is an ex-prisoner.

The episode ends with Marker reluctantly agreeing to give up the job at Kendrick's, and graphically illustrates the problems faced by ex-convicts as they try to reintegrate into society.

"Paid in Full" also contains a scene where Marker visits an antiques shop in Brighton to enjoy his newfound freedom to purchase something with the money he is earning.

Towards the end of the series, Marker works briefly for another enquiry agent, Rylands—in "The Comedian's Graveyard" he is hired to trace a young girl who has run away from her home and is now appearing in a run-down end-of-pier theatre act.

The end credits returned to the original theme music of previous series rather than the barer, more static arrangement that had been used especially for the Brighton episodes.

Several ITV companies in the early 1970s faced strike action as unions demanded better wages for handling the more complex colour broadcasting equipment.

The series opened with "A Mug Named Frank"; some months have passed since "A Fixed Address" and Marker is still living with Mrs Mortimer.

The episode also introduces the new regular character of Detective Inspector Percy Firbank (played by Ray Smith)—a local police officer whose interest is piqued by Marker.

The two gradually come to like each other, even when their relationship is tested—the final episode of the series is "John VII, Verse 24" (29 September 1971) in which it appears Firbank is corrupt and is accepting money from known criminals.

Lighter moments in series 5 come with "Transatlantic Cousins" as a visiting American hires Marker to trace his English relatives, assisted by the tourist's daughter.

", recalls the Brighton era as Marker comes out of hospital and his friends (including Firbank and a returning Mrs Mortimer) attempt to rally round him and cheer him up.

Although Marker would show interest in money if a large quantity of it appeared to be heading his way (such as "Well—There Was This Girl, You See ...") he never considers raising his fees to provide himself with a more comfortable living standard.

For the final half-dozen episodes Marker relocates to Chertsey in Surrey, partly to avoid a clash of location with Gash's business.

This made sense as Euston had a good track record, having scored major successes with Van der Valk, their revamped version of Special Branch, and The Sweeney.

Public Eye became largely forgotten and confined to archival oblivion for almost twenty years, despite being a popular favourite for a decade and a ratings-topper in its time.