“I will look.”

Dean pulled back the blanket and his hospital gown, and made a repulsed noise at the sight of his stitches. “Geez, look at that. That demon got me good.”

Castiel winced as well and covered them over, giving Dean’s leg a gentle pat through the blanket. “I am sorry,” he said again. “I sent you into the lion’s den. We did not think Lilith knew that the last Guardian was dead, but obviously she did and sent one of her demons to fetch it before you could. I am sorry, Dean.”

“To fetch it? Fetch what? The last guardian of what?”

Castiel drew in a slow breath. “Where is the briefcase?”

“Here,” said Sam, and both Dean and Castiel looked at him, surprised that he was awake. He pulled the briefcase from under his chair. “I hope it’s fucking worth it,” he said grimly as he put it on Dean’s bed.

“Yes,” Castiel said. “It is worth it.”

Sam glared at him. “Castiel. What the fuck is going on?”

“I will show you.” Castiel left his hand clasped around Dean’s as he reached across Dean to run his fingers over the top of the briefcase. The locks popped open and soft golden light spilled out.

“What the hell is in there?” said Sam.

“Take it out,” said Castiel. “It won’t hurt you.”

Sam looked at them both, then opened the briefcase and removed a small clay cup. It had a soft white salt glaze, and the faint lines of something thrown by hand on a potter’s wheel. Sam looked at Dean, confused. “It looks old,” he said doubtfully.

Dean looked at Castiel, who was faintly smiling, his fond gaze on the cup. Castiel said softly, “That is the Holy Grail.”

Sam looked as if he was expecting the angel to say more, but of course Castiel had said all he was going to say for the moment. “The Holy Grail — that’s just a story. It’s Celtic mythology recast into Christian themes. It’s a myth.”

“It is in your hand,” Castiel replied, unperturbed.

“The Holy Grail,” Dean murmured and Castiel turned his gaze to him. “In some guy’s apartment in Bethlehem, Pennsylvania.”

“Joseph had a unique sense of humor,” Castiel said. “He liked places that reminded him of the old world. Memphis and Athens and any Salem, of course.” He paused again. “He was the last of the Grail guardians.”

“What does that mean?” said Sam, and at Dean’s gesture gave him the cup. It was heavier than it looked, and felt warm in his hand as if it had been sitting out in the sunshine all day.

“Since the day that Joseph of Arimathea took the cup out of Palestine, a brotherhood of monks, and then knights, has kept watch over it,” Castiel explained. “The Grail grants long life to those who guard it, but they are not impervious to injury. They can die. And over the past year, the few that remain have been murdered, one by one.”

“Lorcan,” said Dean.

“Perhaps,” Castiel said.

Dean realized he was still holding Castiel’s hand, and that Sam was pointedly not looking at them holding hands, and forced himself to let it go. Castiel folded his hands in his lap. “So now what? You take it back to Heaven or something?”

Slowly Castiel shook his head. “No. The Grail is a threshold — it joins Heaven and Earth. Think of it like a door. You cannot bring a door inside — you can only walk through it.”

“So it has to stay here, on Earth,” said Sam.

“Until Judgment Day,” said Castiel, nodding. “Until the day there is no veil between Heaven and Earth. That day is not yet here.”

“Is that why Lilith wants it?” said Dean, and both Castiel and Sam looked at him with surprise. “What? I’m paying attention. If it’s a door, then she wants to walk through it, right?”

“And invade Heaven,” said Castiel. “We believe that is her plan. I am afraid, Dean, you hold in your hand the last of the sixty-six seals.”

Dean looked at the small cup, his heart beating a little faster. “Okay. So. We have to take it somewhere, right? We give it to one of these Grail guardians and they’ll take care of it, right?”

“There are no other Grail guardians,” Castiel said patiently. “They are dead. You and Sam are the new guardians of the Grail, and I am afraid I do not know where it, and you, are to go.”

Dean looked at Sam, who frowned deeply back. “So, we just . . . take it with us?”

“Yes,” Castiel said, nodding. “There is a Grail castle, but like the Grail it has a will of its own. It has been a hundred places that I know of in the last thousand years. It has likely been more. You must find the Grail castle and take the Grail there.”

“Great,” Sam said. “Out of the entire world we have to find one castle that’s never in the same place for long. Any more impossible tasks for us, Castiel?”