"Zero Day" finally arrived and with it an outstanding Person of Interest episode full of suspense, intrigue, action, character drama, familiar faces and an edge of your seat hunt for one of the most important phone calls ever.

Not only was I hooked from start to finish, but the hour brilliantly blended flashbacks with the present dilemma, while revealing a ton of information that connected seemingly singular moments of the past.

There's a reason this is a top-rated show, and the penultimate episode of Person of Interest Season 2 solidified another reason why.

The Machine had been acting rather wonky ever since Reese's former CIA partner Kara Stanton uploaded the virus given to her by the shadowy corporation known as Decima Technologies. Not only was it failing to let social security numbers be revealed in time for rescue, but it was on the countdown to zero and a hard reset.

Except that reset would lead to a telephone call that would give the answerer unfettered access and control of the Machine for 24 hours. Definitely can't have that getting into the wrong hands, right?

Ultimately, the episode was a race of all the characters trying to reach the right phone first. Interestingly, Reese and Finch were split up, but not before teaming with essentially their counterparts.

Reese and Shaw (love her return, she brings a great believable edge to her character) were the guns blazing, ass kicking crew, simply trying to follow Finch in the hopes that not only would they find him, but Root as well. And, after all, who doesn't put trackers on their closest friends? How else can you protect them?

Finch unfortunately was stuck with Root, who had managed to coerce him into working together after threatening to harm his love, Grace. The brains on one team and the brawn on the other.

And yet, through the intense hunt, it was the revelations that made the episode even more interesting than the race against time.

First was the discovery that the Machine was adapting (something we had gathered through it trying to protect Finch during its early stages) and yet this caused the concerned tech to adjust the Machine to simply reset itself and erase its memories and information every night. And in its essentially final hours, it was trying desperately to save and protect itself by printing out all its memories and creating its own number to be saved.

Turning the person of interest into a ghost that was really the machine was a very cool twist. Certainly the show was doing a good job of allowing the piece of super technology to become something more, something perhaps more human? Hopefully, the Machine doesn't go full Terminator with this hard reset.

At the same time, important flashbacks progressed the story along, filling in certain gaps about Finch himself and the machine's early stages at saving people.

It was rather wild to see Finch act so cold with the discovery of Nathan's works of heroism. He didn't care about the "irrelevant" numbers and was simply focused on the greater good. It's such a drastically different sentiment than what he holds now, trying to save everyone he can.

It was even interesting to see Nathan's name pop up right before Finch shut it off in such anger, (he mentioned that it was him alone that created the Machine), and it made me wonder what will change Finch's outlook, as well as what gets Nathan killed.

As much as we saw Finch as a colder character, he was so incredibly warm and loving with his proposal to Grace. This was the woman he loves and it was rather impactful seeing him propose simply through the camera watching them. No words, no closeup shots... and yet I was still able to feel the happiness between them.

I have to admit that I love the use of camera shots throughout the episodes on this show, but it was wild watching those shots tweak out, the intro of the show not work and the flashbacks go glitchy. It really felt like we were seeing everything through the crumbling Machine.

Interestingly enough, when you really think about it, everything centered around Finch. Not only were there hints that Nathan and Finch (who has had plenty of pseudonyms) dabbled in some not so good activity in the past. What's more was that Reese finally learned that Finch was behind the computer that he and Kara had been sent off to get in Ordos in "Matsya Nyaya." And on that computer was the code that started the virus that started the recent countdown for the Machine.

Oh, what a tangled web has been weaved.

Clearly, Finch and Reese are going to have a long talk explaining the claims made by the man working for Decima, but obviously more important things are at hand.

As the fascinating intertwining stories seemed to converge, it was great to see plenty of action as well. The effects for the exploding and flipping car looked pretty good so I can assume that some money was saved for that. Even the gun fight and hand to hand with Reese and the Decima agent were intense.

Carter unfortunately got a little sidelined, but she was dealing with HR and Cal Beecher's murder, something still prevalent but not as interesting as getting to the heart of the story with the machine. Getting set up for murder is not going to help out either.

But it was those final moments and waiting for the traditionally stellar endings of Person of Interest that knocked one last twist out of the park.

Root, who Amy Acker brilliantly makes crazy and smart entertainingly creepy, wants to set the Machine free - and I actually believed she might be the one to get her hands on the call. And she clearly thought she did.

Yet, having Reese, be the lucky guy to pick up the ringing telephone to hear the computerized "Can you hear me?" before cutting to black was the icing on the cake. I'm eagerly ready to watch the finale with that type of closing moment.

This was clearly a top notch episode with so much going on, so many revelations and twists all packed together with that solidly gripping story, characters you love to watch, and a journey worth taking. Now I can't wait to see that final destination and what "God Mode" will do to top it all and propel viewers towards Person Of Interest Season 3.

Sean McKenna was a TV Fanatic Staff Writer. He retired in May of 2017. Follow him on Twitter.