More mystery as Lost nears end

Just five hours remain in Lost's (CTV, ABC, 9 p.m.) riddle wrapped in a mystery inside an enigma.

There's more mystery where that came from, too. Tonight's instalment, The Candidate, promises an Easter egg of sorts, as Lost's resident scold, Jack Shephard (Matthew Fox), the so-called sixth and final "candidate," has to decide whether he can trust the mysterious man-who-looks-like-Locke-but-isn't-really-Locke (Terry O'Quinn).

"Un-Locke," as Lost fans call this mysterious figure, has handed Jack a difficult mission, see, and Jack is once again beset with existential angst.

Back in the real world, Lost writer-producers Damon Lindelof and Carlton Cuse are doling out answers to important real-world questions on their twice-monthly podcast on iTunes. (The Official Lost Audio Podcast is downloadable, free of charge.)

The producers' morsels of information are actually useful to anyone who isn't a Lost obsessive, but may be curious enough to watch an episode or two before Lost ends for good on May 23.

- American Idol's (CTV, Fox, 8 p.m.) final five tackle the Frank Sinatra song book with mentor Harry Connick Jr. Here's hoping they don't come up with Somethin' Stupid but rather stay Young at Heart. Last week's evictee, Siobhan Magnus, said she wanted to perform My Way on the show at some point, if only to get on Simon Cowell's nerves. Sadly, she won't get that opportunity. Instead, we get ... Aaron Kelly.

- Glee's (Global, Fox, 9 p.m.) resident Cruella de Vil, Sue Sylvester (Jane Lynch), is mortified when a lewd video of her performing the Olivia Newton-John classic, Physical, starts making the rounds in the school hallway, prompting a witch hunt to find the culprit. Newton-John herself and Molly Shannon guest appear.

- Russell Crowe alert! Set your DVRs. The tabloid bad boy, Gladiator actor and reputed fan of hotel front-desk clerks is David Letterman's very special guest tonight on The Late Show (CBS, 11:35 p.m.). The musical guest is Sharon Jones & the Dap-Kings