Troi awakens to find herself captured by Romulans. Surgically altered to look like one, she must fake her way though strategy sessions until it is discovered that one of Spock’s underground rebels is using her to create an Underground Railroad for Romulan dissidents. This is a sterling episode with sharp writing and lots of tension. Great stuff that even works “on in island” – if you wanted to introduce people to Trek this might be the best example since Mirror, Mirror.