This trophy requires some set-up. During your initial investigation at the diner, make sure to pick up the copy of The Tempest under the table. Later, when questioning Lucas at his office as either Carla or Tyler, make sure you don't hide the Shakespeare book, so it can be found by Carla or Tyler once they're alone in the office.
Once you finally reach the point where you can combine evidence, pick up the book on Carla's desk, memorize it, and link it with The Tempest (near Tyler's desk). Pick up and memorize The Tempest again, then link it with the employee file on Carla's desk.
If you're only doing this in a single playthrough (and thus have already unlocked
Dine and Dash): chapter select “Face-Off,” make sure Tyler or Carla gets the book, and finish the chapter. Choose “Happy Anniversary” (Tyler) next (don't go back to chapter select), and play through the chapter until you can switch to Carla. Then proceed with the matching steps above.
Solution taken from PlayStation Trophies:
https://www.playstationtrophies.org/game/indigo-prophecy/tro...