What is an example of foreshadowing in the novel, Blood on the River?

In Chapter Six, there is foreshadowing of what is to come when the gentlemen force the commoner servants to cut a path for them through a jungle just so that they can go bathe in a spring. As a result, the men suffer actual physical pain when they come into contact with a poisonous tree. When they reach their destination, all the work continues to be left to the servant class.