The Host (2013)

An unseen enemy has begun taking over human bodies and erasing the memories of the people inside them. When Melanie Stryder is captured, a parasitic alien soul is placed in her body to continue the invasion. But the soul, later called Wanda, does not simply follow her mission. Drawn into Melanie’s fierce need to protect those she loves, Wanda forms a bond with her host and begins to help the remaining free humans.