An unnecessarily complicated murder plan

Question

In the movie "The Conversation", the real plan of the couple is as follows:

Martin Stett had put the idea into the Director's head that his wife was cheating [...] and hired Caul to record them. The conversation in the plaza therefore, was a ruse. The young couple is merely pretending to plan an illicit rendezvous at a hotel when in fact, they are setting up the Director to arrive and confront them, [Wikipedia.]

This doesn't make sense. Why didn't they think of an easier plan, and why did they involve someone else (Caul) in the plan (who could endanger it)?

Answer 1

As seen briefly in the scene where we first see the Director, he is highly suspicious of the story. Even though he treats Caul dismissively, it’s possible that only the “evidence” found by an accredited expert in the field would have been enough to satisfy him that his wife is having an affair. After all, the film suggests she isn’t actually having an affair, and so it’s easy for him to trust her.

There’s other things one might speculate about: maybe he needed to be seen to be emotional for the car crash story to make sense... maybe it was personal on the part of Stett... part of the point of the film is that we like Harry don’t ever get to know all the truth.