In Lepage and Brassard's Polygraph, scene sixteen in an interesting one. The title, "The line up," brings to mind police dramas on TV. The line-up has people who are not guilty, but generally (or so the story goes) one who is.
This play is described as...
... a play noir: part metaphysical thriller, part murder mystery and part love story, played out in a riveting series of overlapping and shifting perspectives.
Francois is always troubled about his understanding of guilt because he never learns the results of his polygraph test, and David may not be all he seems to be. This scene presents three characters in different segments of the play offering more questions than answers. If it is a murder mystery, we can infer that part of the story concentrates on who actually killed Marie—Francois' friend. One of the three shown in the story may be a killer, but there are too many unanswered questions for us to know for certain, even after the play is finished. A great deal of attention is paid to Francois who seems a tortured soul. However, Lucie insists that Francois couldn't hurt anyone. And Francois' torment seems to arise from feeling that he is a suspect, even so long after the event—inferring that he has been unable to leave the past behind.
The other aspect of this scene that seems to be especially significant is that it points out...
...the most telling moments in the play so far.
In other words, it summarizes the highlights to this point, which include Francois working at the restaurant, and being whipped; Lucie's shock at witnessing the suicide at the train, and her initial emotional detachment from the part she is playing; David and Francois crossing paths again so many years after the investigation; and, most importantly (I believe)...
...the 'Film Noir Top Shot' of the handshake in the restaurant.
These images move around during scene sixteen, with a sense of "increasing frenzy." The pace heightens the level of the story's suspense. The overlapping images reflect how the many coincidences there are in the play, which keep the plot moving quickly forward; but the handshake singularly reinforces the many threads that pull these three characters together. David meets Lucie at the train station, and they start to date. Lucie is the actress starring as the murder victim in David's former murder case, but she is also neighbor and friend to one of the police department's prime suspects at one point in the case: based on Francois' friendship with the girl and the fact that he discovered her body.
The line-up may present possible suspects; it may also provide a summary of events so far. But it also strongly demonstrates how quickly the life of each character has become so deeply entangled with the life of both of the others.