I'm a huge non-fan of the Amelia Richardson plot tumor, and I make no apologies for it.
Don't get me wrong - I'm a die-hard Sam Girl and I want Sam to be happy. But his entire year away from Dean with this woman just strikes me as completely ridiculous and unbelievable, and it started from the first scene together back in We Need to Talk About Kevin.
So Sam walks in to a vet's office with this dog, and Amelia is there. They have an extremely awkward conversation about the dog, with him intending to leave the dog there, and her making some non-sequitur saying if "[Sam] was really so great, [he] wouldn't have run over the dog in the first place." After he agrees to take it, she says "There's my hero," in a tone of voice completely devoid of emotion and wearing a Bella-Swan-like facial expression.
I chalked it up to her being new to the cast at first, but it became clear in subsequent episodes that she is just a terrible actress. She and Jared have no chemistry, and their scenes are so painful that I have to fast-forward through them. Even the quality of their flashbacks is abysmal - they'll be talking about cheating high school boyfriends or bladder infections and Sam will get this dreamy look on his face and we'll flash back to Amelia, looking at Sam with her dead, expressionless eyes.
Their scenes appear to be ripped out of The Young and The Restless, with the pair of them discussing their forbidden love (Amelia's married to a Marine who she believed was dead but miraculously wasn't and returned; yes, you read that right) and making plans to meet up for secret rendezvous. It gets particularly egregious in this very episode, wherein they have sex and Amelia walks around in his shirt, and they have this ridiculously inane conversation about how to decide to stay together.
Her acting is spectacularly bad during this scene, and she looks so KStew that I just can't even. I couldn't even focus on Shirtless!Sam.
In addition to the bad acting, we have no history between the two because their story is told in deliberately vague terms and the full story is meant to stay a secret until later; this works okay for Dean's Purgatory adventures, but it really hurts when you're trying to build a romantic relationship. The writers are trying to keep Sam's activities during the year a secret for a later reveal - I get it - but it's killing this story arc even more than the soap opera flashbacks.
Samandiriel has been kidnapped by Crowley, who's torturing him for...information, I guess. Castiel recruits Sam and Dean, they go after the demons, yadda, yadda, and Samandiriel's free. He knows what Naomi's up to, but before he gets a chance to tell Castiel, Naomi gives Castiel orders to kill him, which he does. We end with Sam and Dean back on good terms, and Amelia walking into the empty room where she was supposed to meet Sam.
All in all - this episode is something I think of as Bridge Episode - light on plot itself, but furthering the season arc. We learned that Naomi is guarding the ANGELS tablet and that Crowley is after it, and the Amelia sublot is shelved for now. I predict (hope) they'll get back to hunting and perhaps even discuss what they've been doing the past year in detail, which they are steadfastly refusing to do, despite how much sense it would make.