dead set

The judge at the dog show took points off the Irish setter's dead set because its right ear twitched a few times.

to be at a dead set

I might not graduate first in my class, but I'll make a dead set at it.

The result was that everyone made a dead set on Collins. It was the same in conversation. When he put his head in everyone turned on him. He was roared down unmercifully, with the inevitable result that he lost his temper.