Major Spoilers for Episode 7, Minor Spoilers for Episode 8
Previous to this episode, Roman found out that his 'uncle' was actually his father. This also means that Leetha, who he fathered a child with, was not his cousin, but his half sister. Which makes his baby a bit more inbred than he originally thought. In Episode 7, he does have a moment of shock after realizing this.
Shelley has another good arc in this episode, though it is left hanging at the end. The new body that Dr. Pryce made for her will have a copy of her neural pattern (basically her memories and personality), but this is not a direct download. This means that Shelley as she exists now will die if she goes through with the procedure. More accurately, Dr. Pryce will murder her and stick her decaying corpse in the woods for the cops to find. The police think that Shelley murdered a whole mess of people, so she would have to live in the 'white tower' forever if she were to go on living. Not to mention her crazy hot copy would not be deformed, which is the main reason that she is strongly considering going through the procedure.
The connections about the cult are more or less explained. It's interesting, but the group they have connections to aren't touched on enough for the revelation to be that groundbreaking.
A lot of ground is covered plot wise in this episode, but a lot of it should have been touched upon in previous episodes. Hemlock Grove's weakest trait is its pacing. There is a flashback to the 1800's in this episode, which there hasn't been anything like in the series. It was interesting and might leave you wishing that there was more focus on past time periods throughout the rest of the series. Olivia is very old and revelations about her past are always cool, but there are so few of them. This season at least took this subject on, instead of ignoring like season 1.
Overall, Unicorn is a solid episode. It isn't groundbreaking and won't blow you away, but the performances are good and the action keeps your attention. The ending is quite the cliffhanger. You will need to know what happens next. Good thing that all of the episodes are available all at once.