Star Trek: The Next Generation B-Plot Idea
One of Data's new Holodeck poker opponents describes in detail how he knows that he is a fictional re-creation, not the real historical figure, and that was dreamed into existence by technology. Knowing the Holodeck shouldn't allow this, and Data and La Forge must work to uncover the flaw in the computer's safety protocols and prevent further containment breaches.
Troi realizes that there was no real containment breach, but that Data has been playing poker with acclaimed Argentinian author Jorge Luis Borges and he just talks like that.