In a campaign this is easy. Remember that the four parts of a mission are Intro, Briefing, Mission Debriefing and Outro. Any of these can be missed out. What you are describing is a mission set on Malden consisting of only a Briefing, then a mission set on Everon consisting only of a cutscene, and then a mission set on Malden without a Briefing or Intro.
It looks like one mission, but in fact it is three.