TONIGHT'S MUST-SEES

"American Idol," 8 p.m., Fox. By the end of tonight, we'll know who will collide in the show's finale. Most people expect a battle of the Davids. One (Archuleta) is a sweet-faced teen with a grown-up voice; the other (Cook) is a strong rasp-rocker. Then again, Syesha Mercado keeps tackling big songs and belting them out. We'll see.

"Secrets of the Dead: Sinking Atlantis," 8 p.m., PBS. In the 20th century, researchers finally learned details about the Minoan civilization. Based in Crete 5,000 years ago, it had giant palaces or temples, strong art and the first paved roads. Then it faded. This hour offers new information and surprises. Despite Crete's proximity to Greece, the language has roots in Iran; the people may have been more Asian than European. And the demise? A volcano dealt some destruction, this hour says, but a giant tsunami may have been the final blow.

OF NOTE

"America's Next Top Model" season finale, 7 p.m., CW (Oceanic Digital Channel 93). We're down to the final three now. Fatima Siad, 22, of Boston, and Whitney Thompson, 20, of Atlantic Beach, Fla., are students; Anya Kop, 19, from Honolulu, is in retail sales.

"Back to You" season finale, 7:30 p.m., Fox. It's been a terrific first year for this broadly funny show. Now Chuck and Kelly are ready to tell the world that he's the father of her daughter. Then a new ad campaign makes that difficult.

"The Adirondacks," 9 p.m., PBS. Sprawling across six million acres, the Adirondack Park is easily the largest park in the lower 48 states. About half the land is privately owned; this documentary looks at the land and its people.

"Boston Legal," 9 p.m., ABC. Denny Crane for president? Somehow, this bizarre character is being considered. Tonight, Republican officials look for problems in his past.

"Law & Order," 9 p.m., NBC. A murder reveals multiple levels of deceit, including a complex Internet scam.