Seasons 1 through 4 are considered the core episodes for the series. Wikipedia states:
"...Season four was the final full season of the series. In the two-part season opener, "Steele Searching", filmed on location in London, Mildred Krebs learned of Steele's secret, changing the dynamics of the trio. Other key episodes, including "Forged Steele", "Steele in the Spotlight" and "Sensitive Steele", continued the slow evolution of the romantic relationship between the main characters. Facing a possible cancellation by NBC (whose fortunes had now changed to become the number one network) Gleason contrived a phony marriage between the characters in the final episode of season four, "Bonds of Steele", as an attempt to garner additional interest and provoke NBC to pick up the series for a fifth season."
The show's expected end was interrupted by Albert Broccoli's interest in Pierce Brosnan to replace an aging Roger Moore as James Bond and Stephanie Zimbalist's acceptance of the role of Officer Anne Lewis in Robo-Cop (she would be replaced by Nancy Allen, a role she bacame known for).
Season 5's cancellation was reversed but the standard compliment of 22 episodes were not ordered. Instead, three two-hour movies were broadcast in an abbreviated season. The shadowy character Tony Roseli, a parallel to Remington Steele's character with a murky bacground, was introduced as a rival for Laura's affections.
