Curtis Stone is a guest judge on MasterChef

• In the two-hour season finale of “MasterChef,” celebrated chef Curtis Stone returns as a guest judge as the top three competitors battle in an appetizer round that will determine which of them wins a spot in the finals. (CTV, Fox 14 at 8)

• Archie opens up to his Uncle Frank about his time in the Army after the former learns some unexpected news about his old commanding officer in a new episode of “Riverdale.” Meanwhile, Veronica comes up with a creative way to raise funds. (CW 32 at 8; KTLA at 11)