Moppet polishes and polishes. Captain Daddy runs and runs. As soon as they get inside, the Doctor grabs the charm and steams it up with his breath, huffing and puffing like he's just run a marathon. Moppet stares at him like he's gone mad. The next thing you know, the Doctor's smashing up windows and mirrors all over the ship. He grabs the loot from the captain's quarters, ready to pitch it all into the ocean. "This is the treasure of the Mogul of India!" protests the captain. "Oh good, for a moment I thought it was yours," snarks the Doctor. He insists it's the only way to protect Rory and Moppet and sends the captain back to the storeroom to fetch the crown.
The Doctor delivers the bad news that they might be stuck there for a while, waiting for the wind to pick up because the TARDIS is gone. Once Amy and Rory are down for the night, the captain sits down to have a chat with Moppet. The little tyke is hurt that he hasn't heard from his father in three years. They talk about the boy's mother and feelings and are very sensitive and boring. The boy wants to know why his father would become a pirate. Instead of answering, the captain tells Moppet to get some sleep. Amy hears a woman speaking to her: "You're doing fine. Just stay calm." She opens her eyes and sees a woman wearing an eye patch, smiling at her through a panel in the wall. The panel slides shut and Amy sits up with a start. The woman is gone. The panel is gone. Amy shakes her head like she thinks it's just a dream.
The captain joins the Doctor out on the deck. They talk about the Dog Star and traveling. "I've traveled far like you," the Doctor says. "Space can be very lonely. The greatest adventure is having someone share it with you." The captain gets what the Doctor is saying, but he plans to take Moppet back to London. Finally someone says his name! "Who are you, Henry Avery?" the Doctor asks. Why does a naval officer become a pirate? Well, the pay is probably better and the flag is definitely cooler. Henry thinks his locked into this life, but the Doctor tells him things can change. Like, you could die suddenly! Henry looks thoughtful.
The Doctor wanders into the captain's quarters. Amy comes to talk to him, but he hushes her. He peers through the broken windows. "Feels like something's out there," he says, "staring straight at me." You mean besides the crazy Siren? Thunder rolls in the distance. The ship sways and creaks.
The Doctor runs back out to the deck just as torrential rains begin to fall. Henry shouts some nautical instructions to Amy and Rory. They scramble to work the sails, but neither of them really understands what Henry's telling them. Henry tells Moppet to get his coat, so he can get his compass from the pocket, but the jewel-encrusted crown falls out instead. It rolls across the deck. Moppet gives his father a look of disappointment. The Siren vaults out of the crown, singing, and extends a glowing hand to Moppet. "Don't let her take you!" shouts Henry. Moppet staggers toward her. Henry stares for a while instead of doing anything. By the time he makes a move, Moppet has already touched the Siren and disappeared in a puff of black smoke. The Doctor throws the crown overboard and the Siren vanishes. "You couldn't give up the gold, could you?" the Doctor hurls at him. "That's why you turned pirate!" Well, duh. A mast swings loose and knocks Rory into the water. The Doctor stops her from going in after him. "There's only one thing that can save him now!" the Doctor shouts. He opens a barrel of water. The Siren leaps out. The Doctor tells her to go get Rory, so into the ocean she goes. This seems like a pretty shitty plan to Amy, but the Doctor thinks they can reason with the Siren. He thinks the taken men may still be alive somewhere and they have to follow. With their consent, the Doctor pricks Henry and Amy's fingers. Black spots appear on their palms. The Siren comes to claim them.