Dean convinces "Castiel", who is still Lucifer, to send him back in time to the last reported sighting of the Hand of God which could be useful as a weapon against Amara. Lucifer sees the potential in getting his hands on this weapon so goes along with it and sends Dean to 1944 to the fated submarine mission that sunk the Hand of God. Meanwhile, continuing his charade with Sam while they wait for Dean's return, Lucifer plans his next move.
Sam and Dean investigate a set of murders on Valentine's Day and discover they are dealing with an ancient curse. Once kissed by the curse, the person is marked to die.
Claire believes recent murders in town are supernatural and asks Sam and Dean to investigate. However, Sheriff Mills tells the guys that Claire has been getting into trouble lately and has been attacking normal people and accusing them of being monsters.
