Rebecca Mason was the wife of Tom Mason and the mother of Hal, Ben and Matt Mason. She was killed by Skitters prior to the retreat from Boston.
The Dornia contact Tom in Rebecca's form and tell him about themselves and that his greatest battle with the Espheni is coming. They also reveal that the reason they use Rebecca's image to communicate is because they cannot exist in the same matter as humans, as it is fatal to them. They also inform Tom that Hal is in trouble and that they are creating a weapon capable of destroying the Espheni.
