Dolans Cadillac

In the book "Dolans Cadillac" by Stephan King a school teacher want to kill a man named Dolan.  Dolan is very rich and he killed the mans wife. So he has been fallowing Dolan for a while and then he figures out that he goes to Las Vegas every weekend.  So he joins the road work crew for the summer to get the letter from the road work crew to know where there was road work.  He finally found what he was looking for.  A Detour he was going to dig a hole in the road where the detour was then when he saw Dolans cadillac he would take to detour sign away.  THen Dolan would drive on the road and fall in the hole and die.  This is what I have read so far in Dolans Cadillac.