Collectively labelled the "Lost Generation", they take place in the assorted "gaps" in the timeline; Book #19 takes place between the end of the First Generation and the start of The Sentinels, incorporating an adaptation of the Eternity Comic series The Malcontent Uprisings; Book #20 is set following the beginning of The Sentinels but before the start of the Second Generation, incorporating elements from the plots of Robotech: The Movie and Eternity Comics' CyberPirates''; and the final book, #21, occurs during the period between the Second and Third Generations and details the Invid invasion of Earth.
The "Lost Generation" is a series of books that are set in gaps between different timelines; Book #19 takes place between the end of the First Generation and the start of The Sentinels, incorporating elements from the Eternity Comic series The Malcontent Uprisings; Book #20 is set following the beginning of The Sentinels but before the start of the Second Generation, incorporating elements from the plots of Robotech: The Movie and Eternity Comics' CyberPirates''; and the final book, #21, occurs during the period between the Second and Third Generations and details the Invid invasion of Earth.