What mood is created in this excerpt from Dracula by Bram Stoker?
All at once the wolves began to howl as though the moonlight had had some peculiar effect on them. The horses jumped about and reared, and looked helplessly round with eyes that rolled in a way painful to see; but the living ring of terror encompassed them on every side; and they had perforce to remain within it. I called to the coachman to come, for it seemed to me that our only chance was to try to break out through the ring and to aid his approach. I shouted and beat the side of the calèche, hoping by the noise to scare the wolves from that side, so as to give him a chance of reaching the trap. How he came there, I know not, but I heard his voice raised in a tone of imperious command, and looking towards the sound, saw him stand in the roadway. As he swept his long arms, as though brushing aside some impalpable obstacle, the wolves fell back and back further still. Just then a heavy cloud passed across the face of the moon, so that we were again in darkness. When I could see again the driver was climbing into the calèche, and the wolves had disappeared. This was all so strange and uncanny that a dreadful fear came upon me, and I was afraid to speak or move. The time seemed interminable as we swept on our way, now in almost complete darkness, for the rolling clouds obscured the moon. We kept on ascending, with occasional periods of quick descent, but in the main always ascending. Suddenly, I became conscious of the fact that the driver was in the act of pulling up the horses in the courtyard of a vast ruined castle, from whose tall black windows came no ray of light, and whose broken battlements showed a jagged line against the sky.