Do not engage. Do not look directly at it. Do not react to it. Just keep walking through the forest. Never be alone. Your guide is knowledgeable, cheap, and trustworthy.
You made it through, the guide turns into a horrific beast. You can avoid being surprised by noticing that the guide looks to the side with a perception check.
You make it through without incident, following the guides orders.
You make a mistake and fight a frightening forest creature.
You purposefully look for the monster, the guide abandons you. When you make it out, you notice the old man is not back yet. He never comes.
A woman comes up to your group from off the path. “Excuse me, can I travel with you? I lost my group…” You notice the guide ignores her completely.