Complex sentence: Meanwhile, over the course of the episode, Tom enters a relationship with civilian Ellie Simm (Esther Hall) following an unrelated operation before the events of the episode, going by the pseudonym of civil servant in IT, "Matthew Archer".
Split into simpler sentences: Meanwhile, over the course of the episode, Tom enters a relationship with civilian Ellie Simm (Esther Hall) after an unrelated operation before the events of the episode. Tom goes by the pseudonym of civil servant in IT, "Matthew Archer".