Everyone has their own plan in The Diplomat , and season 3's ending revealed the shocking truth about what Hal (and the President of the United States) was hiding from Kate. This installment of the Netflix political drama picks up after the season 2 finale revealed that President Rayburn (Michael McKean) had died. This meant that VP Grace Penn (Allison Janney) was the new POTUS.
Penn's promotion to president in The Diplomat was pretty complicated, since Kate (Keri Russell) and Hal (Rufus Sewell) had both become aware that it was this VP who was responsible for the HMS Courageous explosion. However, Penn in the big seat, there was little the Wylers could do but work to make Kate the vice president. This is where The Diplomat came in with another surprise, making Hal the new VP