Lost
The pilot of this serial ended with the question "Where are we?" Season 5 asked, "When are we?" One season away from its conclusion, TV's wildest and most inventive mystery felt free to get truly weird, committing to a time-travel story line that delved deeper into the secrets of the Island and took viewers on an Einsteinian ride. But Lost never let its hard-core sci-fi turn get in the way of the characters and relationships that make the show truly compelling. It's a testament to the show's bench strength that it made fans deeply mourn a new character (Jeremy Davies as Daniel Faraday, shot by his own mother — before he was born) while allowing us to see new sides of old friends (especially Sawyer, a.k.a. LaFleur, whose self-discovery and self-sacrifice make Josh Holloway the standout player this season). The finale promises to be the TV event of 2010, and you'd be crazy not to follow it whenever it goes.
(ABC)