Arthur did not panic at first, as drunk people could fall asleep in the oddest places, like peeing or sleeping behind a bush or a tree. Instead, he wandered around the shore and in the nearby vegetation, utilizing his incredible senses to look for anyone who might be hiding, yet there was no one.
One by one, the crew members woke up, recovering from the drinking spree of last night, and when they got better or could speak adequately, Arthur asked questions about the missing person, and at that moment, they all realized someone had indeed vanished.
Panic came but went fast, with Arthur saying he would find whoever went missing and that they should not worry about it. Arthur knew a beast could not have done it, as people would scream, and the beast would probably make a lot of noise.