“Road to War: Iraq” (8 p.m., National Geographic) becomes the latest documentary to try to explain the decision-making process that led to the 2003 pre-emptive invasion.

Over the past few years, “Frontline” has addressed this issue, but often without much cooperation from Bush-administration officials.

“Road to War” includes interviews and statements from former White House Chief of Staff Andy Card and presidential speechwriter David Frum, the man who helped coin the phrase “axis of evil.” Mary Matalin, former counselor to Vice President Dick Cheney, also contributes, as does Richard Perle, a former adviser to the Defense Policy Board, and Nick Calio, former assistant to the president for legislative affairs.

“Road” depicts key players as obsessed about Iraq long before Sept. 11, 2001, and even before Bush took office. Both Card and former Deputy Secretary of State Richard Armitage recall just how quickly post-9/11 conversations turned to Iraq.

Just days after the attacks, talk of Iraq so dominated strategy sessions that Card remembers taking Deputy Secretary of Defense Paul Wolfowitz aside and asking him to put Iraq aside for the moment.

“Road” does a workmanlike job of ticking off the key events between September 2001 and March 2003 when the invasion began. But the rationale for the singular focus on Saddam Hussein remains rather murky.

As in many documentaries, Cheney is depicted as a forceful proponent of the invasion and the philosophy that a post-Hussein Iraq would become a beacon of liberty and help transform the Middle East.

In a 1994 C-SPAN interview now ricocheting around the Internet on YouTube, Cheney defends the first President Bush’s decision not to invade Iraq, occupy Baghdad and topple Saddam. He argues that we would have been “all alone” in our occupation and that it could lead to a disintegration of the country, a destabilization of the region and a potential “quagmire” costing too many American lives.

How did Cheney’s thinking change between 1994 and 2003? Perhaps that it the essential question and the only way to explain the “Road to War.”

Tonight’s other highlights

• On back-to-back episodes of “Prison Break” (Fox), a question for Warden Pope (7 p.m.), key evidence found (8 p.m.).
• A substitute teacher proves demanding on “Everybody Hates Chris” (7 p.m., CW).
• Terror at home on “Kyle XY” (7 p.m., Family).
• “History Detectives” (8 p.m., PBS, check local listings): stories surrounding a letter from Lincoln, a Quaker map and the USS Indianapolis.
• Mohinder’s father arrives in New York on “Heroes” (8 p.m., NBC).
• An auditor’s last ledger on “The Closer” (8 p.m., TNT).
• Scheduled on “Dateline” (9 p.m., NBC): A land dispute between rural neighbors culminates in homicide.
• A visit from a college friend makes P.J. realize how much she has changed on “My Boys” (9 p.m., TBS).
• A reporter’s ruse turns deadly on “Saving Grace” (9 p.m., TNT).
• Anthony Bourdain samples the cuisine of Cleveland, Ohio, on “No Reservations” (9 p.m., Travel) .
• Actor and activist Ed Begley Jr. dispenses advice on how to live the green lifestyle on the second-season premiere of “Living with Ed” (9:30 p.m., HGTV). Look for cameos by Daryl Hannah, Bradley Whitford, Jane Kaczmarek, Sharon Lawrence and Jackson Browne.

Cult choice

Catch the Brat Pack at their peak in the ludicrous 1985 melodrama “St. Elmo’s Fire” (7:30 p.m., Oxygen).