A piece of the original Ark of the Covenant, referred to as a Hand of God, is found by the Nazis' archaeological branch, known as the Ahnenerbe. A Woman of Letters, Delphine Seydoux, is sent undercover to retrieve it from the SS Officer Befehlsleiter Gumprecht. Upon confirming its authenticity, Delphine first stabs Gumprecht in the neck and then the gut, before she steals away with the Hand of God onto the USS Bluefin for transport to the U.S. with the intention of bringing it to the Men of Letters Bunker.
When Sam and Dean discover the existence of the Hand of God in 2016, they have "Castiel" (Lucifer) time travel with Dean to 1943 to retrieve it from the ill-fated USS Bluefin before the sub is lost forever. Due to Delphine placing specialized warding sigils on the sub, Lucifer is not able to get past the hull, allowing only Dean to make it on the sub.
Dean tracks down Delphine on the sub. While talking to her, he says her name, which causes Delphine to put a knife to his neck since no one on the ship knows her name. Dean comes clean to Delphine and the sub's captain about being a member of the Men of Letters from the future, and that the ship will soon be sunk. While the captain dismisses Dean's claims, Delphine continues speaking with him and telling him of the warding she placed on the sub to protect the Hand of God from supernatural interference. Dean tells Delphine they will need to clear the warding to allow him to go back to 2016. He asks Delphine to give him the Hand of God, telling her he is fighting his own Biblical war in the future. Delphine agrees and begins breaking the sigils painted on the ship. However, the final one is carved on her chest, making the spell bound to her heart; the only way to break it is to kill her. Dean refuses, but Delphine insists that it's the only way. As Dean is about to drive the knife into Delphine, the ship is attacked by a German destroyer.
Meanwhile, at the Bunker in 2016, Sam hits the books looking for a way to retrieve Dean. He finds a spell that will clear the warding, but is discouraged when he realizes that it requires the power of an archangel. Lucifer begins the spell despite Sam's protests that "Castiel" is not strong enough to survive the casting. In desperation, he offers to let his friend touch his soul in order to gain the power that Sam thinks he needs. Lucifer realizes that he will have no use for Sam once he has the power of the Hand of God, and therefore no reason to keep him alive or continue to pretend to be Castiel. He reveals his identity, attacks Sam, and is preparing to kill him via soul-touch when Castiel takes control of the vessel and stops him. Sam tells Castiel to expel Lucifer but the angel refuses, saying that they need Lucifer's power to save Dean.
Dean, Delphine, and Petey Giraldi make it to the operations room, where Delphine is shocked to hear the voice of Befehlsleiter Gumprecht over the radio; he survived due to being a member of the Thule Society. Gumprecht offers Captain Deerborn a deal -- Delphine and the Hand of God for the highest of P.O.W. treatment for the Bluefin crew. Dean asks Delphine to show him how he can use the Hand of God to save them. Delphine denies him, out of worry he will be killed and the Hand of God will just end up back in Nazi hands. She tells Dean that the Bluefin crew were meant to die and now they will do it with purpose. Delphine takes the Hand of God into her hand and is imbued with its power, becoming bathed in a blinding white light that destroys the sigil on her chest, allowing Lucifer to retrieve Dean and the Hand of God.
Upon Dean and Lucifer's return to the Bunker, Sam reveals Lucifer's identity. The archangel grabs the Hand of God and tries to power up, but the artifact is now empty of power. Lucifer goes to kill the Winchesters, but Sam is able to use an angel banishing sigil to banish Lucifer from the Bunker. Sam and Dean then vow to save their friend and Sam lets Dean know that while the wreckage of the Bluefin was never found, the German destroyer was, leaving Dean contemplating the sacrifices of the sub's crew.
(playing while Delphine kills Befehlsleiter Gumprecht in Nazi Occupied France, and when Dean is sitting alone on the dock)
Sam: Hey, did you know the Nazis had a special branch devoted to archaeology? Dean: Little early for Nazi trivia, especially without caffeine.
Lucifer: How are your wounds, doggie?
Crowley: They are... no less than I deserve. Lucifer: Aww, you're scared of your master. That's a good doggie. But it's an act. I broke you, but um, yup I can still smell it. You've got that delectable little whiff of defiance. You're just playing, huh? Waiting for your moment to retake the throne. Am I right?
Crowley: Yes sir.
Dean: You need to stay here.
Sam: Stay here?
Dean: Just in case things go sideways, somebody needs to be left standing to take care of the Darkness. We can't risk us both! And at the moment, I'm the least valuable player, you both know that I can't kill Amara! So the least I can do is get the thing that we need so that you can!
Dean: Captain James Dearborn, my name is Dean Winchester and I am on a mission from the future, the details of which I am not a liberty to discuss. But know this: within the hour, a German destroyer will find and attack this submarine and you will go down.
Dean: From Man of Letters to Man of Letters I'm fighting a war in the future. It's not like your war, it's big. Biblical, end-is-nigh big. And I need your weapon to win. That is why I came.
Lucifer: Oh, it's ju- I don't, I don't need you anymore. I mean, Dean's the one with the link to Amara. Why have I been trying to spare you? I mean, maybe it's because you're like the girl who kept turning me down at the prom. I will touch your soul, just because you asked so nicely. And I'll use your spell to blast through the warding and retrieve Dean and the, um, Hand of God. And then when Dean comes back and he finds this place decorated with your guts, I will tell him the truth, Sam. I'll just say, 'Dean -- Dean... he knew the risks, he wouldn't take no for an answer.'
Lucifer: In the flesh.
Dean: Teach me how to use it. It's the power of God. Maybe I can use it to save you, save the sub.
Delphine: And your war? Dean: I wanna help you now.
Delphine: You save this ship, get us to the surface, and then what? The power of God will consume you, and you'll have merely brought the weapon closer to the Nazis' grasp. We are supposed to die, let us do it with a purpose.
Sam: Cas? Why? Castiel: I wanted to be of service to the fight. And only Lucifer can beat her.
Lucifer: Mmm, I feel a burden lifted. You know, this whole 'deep cover' thing, it just wasn't, it wasn't terribly well thought out. Donning this-this Cas mask? This grim face of angelic constipation? Just ugh. And then teaming up with you two. I mean, I thought you boys were insufferable as mortal enemies. But, working with you? Ugh, that's the soul crusher. Why the faces, boys? You should be cheering. We have a common enemy, and with this she will be no problem. I mean, I will have killed you both by then, but still, come on.
Sam: So how'd you get through today? I mean, what did you do?
Dean: Nothing. Sam, they... I was just a witness. Sam: Do you want to talk about it? Dean: No. No, story for another day. Hey, the, uh... The German ship that sank the Bluefin, what happened to it?
Sam: It went down. Unlike the sub, its wreckage was found. Um, there was a giant hole that'd been ripped through the entire thing, something must have hit the fuel tanks, it exploded. But it burned, sank.
Trivia & References
The song "Non, je ne regrette rien" was recorded by Edith Piaf in 1959, although the episode is set in 1943. Writer Robert Berens made the point that the song was non-diegetic and used as Delphine's theme.
Delphine: I have lived a hard life, but these months? Pretending to love a Nazi cochon like you has been the worst. But this moment, watching you die? It is the best. The Men of Letters send their regards.
Sam: It was World War II, kind of an 'all hands on deck' situation, y'know?
Dean: Yeah, Rosie the Riveter. Cool.
Rosie the Riveter was an icon used in U.S. government campaigns during the Second World War to encourage women to work in industries supporting the war effort. In more recent years, she is often used as an emblem of feminism.
As Sam is reading Dean one the transatlantic cables between Delphine and Clifford Henshaw, the final paragraph includes the line:
Sam: Well, yeah, I'd say so. I mean, tides took the wreckage, submersibles have been trying to locate it for years. I mean, if James Cameron and his Avatar billions can't find it...
Dean: Yeah, but we have something James Cameron doesn't have.
James Cameron is a filmmaker, known for movies including The Terminator, Aliens, Titanic and Avatar. He has been on expeditions in submarines to some of the deepest points in the ocean. Cameron also made the TV series Dark Angel in which Jensen co-starred for the second season.
Lucifer: Well then, tell me, once and future King of Hell. You've been watching my rule. What treasonous thoughts do you have brewing in that little head of yours, huh?
The Once and Future King, is an Arthurian fantasy novel by T.H. White. The book deals with the concepts of human nature, power and justice.
Dean: That sub is a tin can floating in the middle of the ocean, doomed to go down. You can't really mess with history at 20,000 leagues. So we get in, get the weapon, get out. It's a milk run.
20,000 Leagues Under the Sea is a book by French author Jules Verne published in 1870 which followed the travels of Captain Nemo aboard the submarine "Nautilus."
Sam: So you expect me to sit here and ride the pine, while you and Cas go play Jules Verne?
The Queen of Sheba was a queen regent who flaunted her wealth while visiting King Solomon in the Bible. Someone is referred to as the "Queen of Sheba" when they are treated in a preferential way, which may or may not be deserving.
Gams used to be slang for a woman's legs.
Giraldi: He took my clothes and he hog-tied me in the head, this guy.
Dean: That's the Hand of God? Doesn't look like much.
Delphine: No, I suppose it doesn't. It must have been more impressive in its complete form -- the Ark of the Covenant. Dean: Oh, so full-on 'Raiders.' That's, okay...
The Ark of the Covenant is an object from Biblical lore from the second book of the Torah and the Hebrew Bible (the Old Testament). It was made by the prophet Moses to house the stone tablets containing the Ten Commandments which God gave to him.
Raiders of the Lost Ark is a 1981 movie in which adventurer and archaeologist Indiana Jones tries to stop Nazis from finding the Ark, which they believe will make them invincible.
Giraldi: Okay, then. The next president.
Dean: Eisenhower. No! Uh... Truman. Now would you please shut up?
In the scenes before and after this one, Lucifer is in Castiel's navy suit jacket. While in the second he goes to get Dean, he appears to be dressed in a black trench coat, he is still his navy suit jacket, only his lapel had become undone.
Casifer appears to be wearing a black trench coat.