You all debate for a bit about the best course of action, but eventually those that suggest simply charging into the path outvote all others. You agree to get into your cart and Bell snaps the reins and the horses charge forward. These horses are not war horses and built strong only to pull whatever load is in the cart. They have blinders, but the graveyard is still terrifying.
After a minute of the horses going at a gallop, you all hear the sounds of predator animals to your left and right. You aren't sure if the animals are actually there or a manifestation of dark magic, but the horses start to act as though the are under threat. As they panic, they pull you into a fog that is so thick you can only see about 10 feet before it is just white mist (heavily obscured).
OOC:
I need an animal handling check from someone, presumably the driver. I like the rethinking of tool checks where all tool checks are really just skill ability checks, but proficiency in the tool gives advantage. As such, if someone has proficiency in vehicle (land) and makes the check, they have advantage. As such: no vehicle proficiency is just a normal animal handling check. With tools it is an animal handling check with advantage. If you have vehicle (land) tool proficiency but no proficiency in animal handling, it is still an animal handling check but with advantage.
Success (DC 20): you calm the horses
Failure (but 16-19): you can either fail or calm the horses at some cost (it must be a cost that is meaningful)
Failure (15 or less): horses panic so much that they break free and dash back the way you came, leaving the cart stranded