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Another brilliant promo trailer has been dropped by Netflix for "House of Cards" season 4.

The latest teaser hints at one of Frank Underwood's (Kevin Spacey) deepest, darkest secrets that involve the DC train tracks.

Back in season 2, then-Vice President Underwood met up with journalist Zoe Barnes (Kate Mara) at a subway station to urge her to delete all information that would link him to Congressman Peter Russo's (Corey Stoll) death. But viewers were startled when Underwood suddenly pushed Zoe to death in front of an oncoming train.

The trailer for season 4 seems to address Underwood's past crime by incorporating the train track in his slogan "Putting America back on track."

While the plot for the fourth season of Netflix's original political drama is still under wraps, the possible exposure of his secret could cause great damage to Underwood's presidential re-election campaign. Will his murderous past keep him completely out of the White House?

"House of Cards" released the first trailer for season 4 during one of the commercial gaps of the GOP debates on Dec. 15. The trailer showed the Underwood-approved message for his own campaign that detailed his plans if he returns to power after the election.

At the end of season 3, the U.S. president and his wife Claire (Robin Wright) were having marital problems. Claire even decided to leave Frank despite the pressure for them to stay together for the sake of the campaign. Will she ultimately end their marriage even if she knows that it could greatly affect his bid for re-election?

Netflix is scheduled to release "House of Cards" season 4 on March 4, but fans can still catch up on the episodes from the previous seasons on the entertainment streaming website.