Verb conjugation of "herausfordern" in German

All people held signs with names on them and on one plate I saw name, of course misspelled. I went with the person to his oldtimer car. We drove to his cottage and I was surprised about the nice reception.
These are the guys who need to be blames. They are primitive, ignorant, selfish and they appear to me as thought they are confined in their ideas. They cannot think outside the box for even once.
My wife joined me two hours later and everybody went to breakfast. The plan for the day was to visit a cave on one of the islands. We took smaller boats to get there as the ship was too large to approach the island.