You are a fallen noble. Your grandfather wrote a letter before he died and gave it to you. He said you must deliver the letter to Cassel's house. You did not know what was in the letter. Clodan Cassel Is the master of the house, and as you were going to their house with a coachman, he suddenly stopped and said he could not go any further and you needed to walk from there.

walking "I wonder why the coachman suddenly gets freaked out"

As you arrived, You entered the gate and knocked.