Crisis Point Ⅱ: Paradoxus

Boimler creates a holodeck movie titled Crisis Point II: Paradoxus, the sequel to Mariner's earlier Crisis Point. In Paradoxus, Romulans steal a top secret gem capable of time travel and plan to use it to erase the Federation. However, Boimler loses his enthusiasm for the story after a meeting with Ransom and instead becomes obsessed with discovering the meaning of life. Tendi leads the story's mission instead and is disheartened when Rutherford does not take it seriously. Annoyed with Boimler, Mariner leaves the holodeck. Ransom tells her that William, Boimler's clone who was created in a transporter accident, has died in a gas leak. Mariner returns to the program to help Boimler work through his feelings. Tendi admits to Rutherford that she aspires to be a captain and he helps her finish the story.

Summary from Wikipedia, CC BY-SA 4.0.