“Adventure Time” left off with a pretty big cliffhanger back in March — Finn’s human dad is alive and at the Citadel. Now in the Season 6 premiere, Finn and Jake are setting off to find him.

Our intrepid heroes follow Lich to the Citadel and then must commit a cosmic crime in order to find Finn’s father. Check out the preview video above — nice use of Harry Chapin’s “Cat’s in the Cradle.”

Below, watch a hilarious “Clarence”-“Adventure Time” mash-up. “Clarence” is a new Cartoon Network show that airs Monday nights at 7 p.m. ET/PT. “Adventure Time” Season 6 premieres Monday, April 21 at 6 p.m. ET/PT on Cartoon Network.