Mackenzie Allen, who serves as Vice President of the United States, has a tough decision to make, whether or not to go against the wishes of the dying current President. He has asked her to step down and let someone a little more appropriate take his place in the Oval Office. However, it's not only the President that is calling for her resignation, it's her entire party which elected her as the Vice President to start with.

As Mackenzie begins the transition into the office of President, she has to select a Vice President, a situation in which Nathan Templeton tries using to his advantage. Mackenzie's daughter, Rebecca, faces a crisis when her diary goes missing, which contains information about her mother that could hurt her.

Faced with her first national crisis - the death of nine DEA agents in Latin America - Mackenzie shows strength and resolve in dealing with a corrupt leader. Meanwhile, Nathan Templeton is approached by an ambitious congressman who served with Mac's Vice Presidential candidate, Warren Keaton, and is eager to divulge potentially damaging info in an effort to derail his nomination. Mac's teenage twins resume public school, only this time it's complete with secret service detail and press spectacle, and while popular Horace welcomes the attention, shy Rebecca finds it overwhelming.

In the middle of the announcement of her new National Security Advisor, Anthony Prado, Mac is caught off guard by the breaking news of a terrorist smuggling explosives across the Canadian border. The way in which Mac and her Attorney General deal with the situation pits them squarely against each other, and Nathan Templeton takes great pleasure in publicly second-guessing Mac's every move. Meanwhile, it's Halloween, and Amy - who desperately wants to go trick-or-treating like a normal kid - is disappointed to learn that, due to security concerns, she may have to settle for a party this year instead. When Rod as First Gentleman finds himself fodder for late-night comics, it hits his son Horace especially hard.

When a destructive hurricane hits Florida, Mac and Templeton fly to Florida to survey the damage. While there, Mac learns of an emergency situation with an oil tanker off the Florida coast which could have devastating consequences. Meanwhile, Rod is seriously considering an offer to become Commissioner of Baseball.