Complex sentence: Meanwhile, Martha has been making her own way to the Source via the surface with a Hath who dies saving her from quicksand; devastated, she reunites with the Doctor and Donna near the Source shortly before both armies arrive.
Split into simpler sentences: Meanwhile, Martha has been making her own way to the Source via the surface with a Hath who dies saving her from quicksand. Devastated, she reunites with the Doctor and Donna near the Source shortly before both armies arrive.