This is a really interesting study of how women are represented in science fiction films since, essentially, the birth of that medium-genre. Unsurprisingly, that representation is either absent or minimal at first, and over the next 120 odd years its main feature is oscillation. Conrad makes the argument that progress towards realistic, diverse roles for women is both impacted by historical events and non-linear. For instance, there's a surge in female representation prompted by WW1, that not only gives women greater roles (aiding in the defence of country, for example) but also holds them up as potential victims of military invasion in a sort of now-you-have-it, now-you-don't granting of agency. Such brief steps into prominence rarely last, however, as conservative backlash returns women to supporting or stereotypical roles. This alternating effect is noted in a number of eras, with a number of different characters, and is especially noticeable in franchises like Planet of the Apes, where the initially impactful Dr. Zira is watered down or replaced entirely in the later films. It's very much two steps forward, one step back, but overall positive change is apparent, and Conrad's tracing of all the undercurrents prompting this evolution is both convincing and compelling.