With all of the talk about “reality” television, the quiet sophomore success of a solid drama like “The Guardian” (8 p.m., CBS) can go unnoticed. The legal drama has made its Australian-born star Simon Baker a bit of an American idol. “The Guardian” consistently shows well against strong competition, including “Frasier” and “24.”

Baker’s character, Nick Fallin, has a complex relationship with his thick-skinned lawyer dad, Burton (Dabney Coleman). Tonight’s strong episode belongs to Burton, who discovers that his old boyhood pal is suffering from cancer and that his son, a Gulf War hero, is raising money for a charity to help Burton’s struggling hometown. Nick has a more cynical take on the young man’s charity scheme. And that puts him in the odd position of reining-in his father’s rare stab at altruism. Tonight’s episode is effective enough as it is without the kind of “surprise ending” that happens all too often during sweeps months. That said, the last few minutes of tonight’s “Guardian” should make you jump out of your seat.

Are there alligators in New York City’s sewer system? Do men think about sex every seven seconds? Does calling the 809 area code result in a big phone bill? Did Courtney Love’s dog die after eating her breast implant? Are any urban myths true? Find out on “MTV’s Big Urban Myth Show” (9:30 p.m., MTV), an offbeat exploration of strange and persistent stories that have become accepted legends.

“Scientific American Frontiers” (8 p.m., PBS) examines the “placebo effect” and the possible reasons why patients given pills containing only sugar often feel much better.

Some medical experts theorize that patients who respond positively to placebos may really be reacting to the sympathetic ear and comforting manner of the doctors or nurses who prescribe the ersatz medication. UCLA researcher Andrew Leuchter theorizes that humans may be “hard-wired” to feel better when under the impression, however false, that somebody cares.

Tonight’s other highlights

• The 2002 documentary “A Letter From the Deep” (6 p.m., Cinemax) examines the loss of the Russian submarine Kursk in August 2000 and the death of its 118-man crew.
• Auditions continue on “American Idol” (7 p.m., Fox).
• Lorelai berates Jess for taking Rory for granted on “Gilmore Girls” (7 p.m., WB).
• Marie’s past may explain her motivations on “24” (8 p.m., Fox).
• The father of a pop singer tries to protect her from commercial exposure on “Judging Amy” (9 p.m., CBS).
• Miguel faces a government crackdown on “Kingpin” (9 p.m., NBC).
• A father is accused in the “honor killing” of his daughter on “NYPD Blue” (9 p.m., ABC).

Series notes

After ejecting from his jet, Chegwidden braves the elements on “JAG” (7 p.m., CBS) … Bob Eubanks is host of “The Most Outrageous Game Show Moments 3” (7 p.m., NBC) … Asleep on the job in “8 Simple Rules” (7 p.m., ABC)… The gang regroups after tragedy on “Buffy the Vampire Slayer” (7 p.m., UPN) … Cheryl is mugged on “According to Jim” (7:30 p.m., ABC).

Gym tales told on “Frasier” (8 p.m., NBC) … Carl Reiner and Teri Garr guest star on “Life with Bonnie” (8 p.m., ABC) … Pink slips on “Abby” (8 p.m., UPN) … Martha falls into a coma on “Smallville” (8 p.m., WB). Adam woos a geriatric jury on “A.U.S.A” (8:30 p.m., NBC).

Late night

Vince Vaughn and Jay-Z appear on “Late Show with David Letterman” (10:35 p.m., CBS) … Jay Leno welcomes Barbara Walters, Meredith Vieira, Star Jones and Joy Behar (“The View”), Trista Rehn (“The Bachelorette”) and Ben Taylor on “The Tonight Show” (10:35 p.m., NBC).

Christopher Walken, Laura Prepon and Nada Surf are booked on “Late Night with Conan O’Brien” (11:35 p.m., NBC).