Here it is...
Alright, long story short…
HG Wells is a high school teacher thanks to an artifact that wiped her memories. Sykes is after her because she holds the key to getting into a Regent safehouse. Myka and Pete get to her first, but Jinks and Marcus Diamond (who can’t die) kidnap her. Claudia, Myka and Pete get the artifact that holds the hologram of HG that we’ve been seeing all season and Pete and HG decide to destroy it to keep Sykes from getting any info. Jinks and Marcus intervene but Claudia grabs the artifact and runs off. Jinks chases after her only to tell her that he’s actually undercover for Mrs. F and Jane and gives her the meeting place of where Sykes has “Emily.” Claudia in return gives him the artifact. When Claudia asks why he would go undercover for such a dangerous mission he says that he couldn’t protect his sister, but he can protect her. He leaves with Marcus.
Claudia happily gives the info to Myka and Pete, who all race to the place that Sykes has “Emily.” But they’re too late, and all they find is Jinks, dead. Claudia is heartbroken (Allison S. nails it here, if your eyes don’t well up when she screams in pain at finding his body then you’ve got a heart of stone).
Jane attempts to comfort Claudia who angrily responds that the Regents are cowards and that Steve was worth a 1,000 of them.
Marcus Diamond kidnaps Leena and blows a cannonball from Blackbeard’s cannon to make the Warehouse raise its protective barrier.
Myka and Pete find Sykes and HG (who has her memories put back). Sykes has a riding crop artifact that makes a person do whatever he wants - he forces HG to hold Myka at gunpoint so she can tell him how to access the Regent sanctuary (it was built by her old mentor). She gives it to him and they cross over to the Warehouse.
Sykes gets his bracelet and then attempts to make Pete shoot himself to cause Jane the pain she caused him. He is defeated by the agents and attempts to go back into the Regent barrier after Jane (who has entered the sanctuary) but is cut off, leaving nothing but the bracelet.
Mrs. F shows up to rescue Leena, claiming that she made a promise to her and she intends to honor it. However, Claudia emotionlessly finds the artifact that is keeping Marcus alive (a metronome) and kills him. Mrs. F wants it back, but Claudia refuses - she’s tired of arbitrary rules and is planning to bring Steve back with the metronome.
Sykes set up a bomb in his old wheelchair to go off in the Warehouse, and the agents can’t get out due to the force field still set up. HG manages to bring a small portion of the force field to cover the agents and says goodbye, at peace while she dies.
As the Warehouse dies, so does Mrs. F.
Pete claims they have lost as the Warehouse is destroyed, but Artie holds out the watch he received from MacPherson last season and says all hope might not be gone yet.