Assignment, The

Dr. Rachel Kay (Sigourney Weaver) is a rogue doctor with a weird vision of a better world after losing her brother to a contract killer Frank Kitchen (Michelle Rodriguez). In an experiment to assess how much physical identity matters, Kay performs a sex-change operation on Kitchen to have him start over.

When Kitchen finds out the operation cannot be reversed, she kills almost everyone involved in the sex change and cuts the fingers off Dr. Kay, so she will not practice again.