be set on something/on doing something

be (dead) set on (something)

To have a strong (and sometimes inflexible) desire for something. We were all dead set on traveling to Spain for the summer, until Lizzy broke her leg and we had to cancel it. I wanted to spend the money on a new car, but my husband was set on getting new furniture for the living room.
See also: on, set
Farlex Dictionary of Idioms.

be (ˌdead) ˈset on something/on doing something

want to do or have something very much; be determined to do or have something: She’s dead set on leaving her job and emigrating to Canada.
See also: on, set, something
Farlex Partner Idioms Dictionary
See also:
  • be (dead) set on (something)
  • be dead set on something
  • travel on (one's) own
  • fill or kill
  • FOK
  • cancel (one's) Christmas
  • cancel Christmas
  • cancel someone’s Christmas
  • opportunity
  • a golden opportunity