How does the author use foreshadowing in Foucault's Pendulum?

There is a great deal of foreshadowing in the narration because the narrator knows that certain events will ultimately lead to the unhappy fate of having to track down a kidnapped friend after hours in a Parisian museum. Once the narration picks up with Casaubon in the museum, the narrator becomes more tentative and provisional, presumably because he does not know what is going to happen.