Soak the ears of corn in water for at least 30 minutes.
Preheat a grill on medium-low to medium heat.
Place the ears of corn directly on the grill. If you have a large flame, you may want to stick a tin pan under the corn to avoid direct flame contact, which would char the husk too quickly.
Turn corn every 5 minutes or so for about 20 to 25 minutes. The husk should end up nicely browned, a little charring won't hurt it. You can test the doneness by peeling back a husk and checking the crispness of the kernels. They should be firm and juicy.
You can leave the corn in the husks until ready to serve, then peel the husks completely, spread with butter and salt and pepper to taste.