That was some damn interesting backstory on Person of Interest

Last night's Person of Interest solved a mystery that fans of the series have probably been wondering about ever since we saw how Reese was burned by the CIA. Plus, we met a new character who knows things about the Machine that might be news even to Finch.

For most of this episode, we followed the Machine's memories back to 2010, the year before Reese and Finch started working together. Finch has hired a skanky mercenary dude named Dillinger to do his heavy lifting, but mostly the guy just shoots people and then tries to have sex with any ladies who happen to come up as the numbers of the week. It's obvious that this dude has got to go.

That was some damn interesting backstory on Person of Interest

As we watch Dillinger's final job for Finch unfold, we discover that the lives of Finch, Reese and Shaw were entangled long before they started officially working together.

The number of the week back in 2010 is a guy named Daniel Casey, a computer security consultant who has been brought in to do some highly classified government work. Pretty quickly, he realizes that he hasn't been hired to defend the system he's working on. The government wants him to break into it. Of course, it's the Machine. And Casey has enough computer geek ethics to realize that something seriously shady is going on, both with the job and with the system he's hacking.

Decima, Control, and the Briefcase Connection

So Casey saves some code from the Machine and tries to turn whistleblower on the government. Which of course grabs the attention of Control and her intelligence buddies, who promptly send Reese and his evil partner Kara Stanton to kill Casey and grab the briefcase full of the Machine's code.

That was some damn interesting backstory on Person of Interest

Oh and by the way? Control casually admits that her gang killed Nathan Ingram, the man who helped Finch invent the Machine. So in case you were wondering, that is what happened to Ingram.

The Machine code briefcase also grabs the attention of Greer, the mysterious British guy who runs the evil company Decima. Yes, that's right — the same Decima that unleashed a virus on the Machine, and now owns the code for the Machine-like AI Samaritan. So many conspiracies in play here!

When Dillinger realizes that he's up against trained government agents, he decides it's time to quit working for Finch. This is way above his pay grade. So he dumps Casey off at Finch's library, and starts planning an exit strategy. While Finch and Casey bond over their hacker ethics, and Finch gets Casey some new IDs (and, most importantly, a clean phone), Dillinger is supposedly out getting Casey tickets out of the country. But of course he's not. He's actually trying to sell the briefcase to Chinese intelligence operatives. Of course, you knew he'd pull shit like that after he spent hours sharpening a knife he called his "Blackwater souvenir."

That was some damn interesting backstory on Person of Interest

Does Casey look kind of like Edward Snowden to you? Sexy hacker whistleblower hiding in a snowy land?

But just as Dillinger is handing of the briefcase to the Chinese, a hooded operative from Control's gang comes into the picture. She takes everybody down, including Dillinger, except for one guy who runs off into the woods. It's Shaw, and she's on one of her first missions.

So let's unpack all the connections here. First of all, Reese left the CIA after they tried to kill him and Stanton in China, when the two agents were on a mission to retrieve this briefcase. He felt massively betrayed and the briefcase mission became a symbol to him of everything that was wrong with intelligence work. But two seasons ago, Greer said poisonously that Finch was actually the person who owned the briefcase in the first place. Many of us, including me, have been wondering WTF he meant. Was he lying? Was Finch actually more involved in evil than we realized?

Nope and nope. Finch did lose the briefcase, mostly by hiring a Blackwater skank. But the hit on Reese was ordered by Control. And the Machine virus was totally a Decima project. Nicely wrapped up, show.

When Finch First Laid Eyes on Reese

Basically Casey's number of the week moment was the first time that the Machine Gang was working together, though they didn't realize it. As a result, we get to witness Finch's love-at-first-sight moment with Reese. Reese's evil partner Stanton, who loves torture people for fun and later tries to kill Reese, is all set to murder Casey just because Control told her to. But Reese has second thoughts. He doesn't think that Casey has done anything wrong, and he's starting to question this whole CIA game anyway.

As Finch watches from his car, Reese hands Casey some cash and Canadian IDs, telling him to get the hell out of the country before anybody else has a chance to murder him. We see Finch's eyes practically welling up with tears of adoration. Here, at last, is a man with muscle and integrity. Unlike Dillinger, this is a guy who can take down a bar full of heavies but still make an ethical judgment call at the end of the day. Though Reese's reasoning, that he saw innocence in Casey's eyes, isn't exactly a great way to decide who is a bad guy. But WHATEVER. Finch is in love. We now know why he sought out Reese in the first episode of the series.

That was some damn interesting backstory on Person of Interest

We also know that Casey may be about to play a big role in this season's final episodes. Once we're back in 2014, we see that Casey has made a new life for himself in a rural cabin somewhere in snowy Canada. But then, just when he's settling in for an evening surfing the internet by the fire, there's a knock at his door. It's Root, with the Machine whispering in her ear, with a message for Casey. "We have a mutual friend," Root explains, "And she needs your help."

Like I said earlier, I think that it's likely Casey knows something about the Machine's software vulnerabilities that Finch doesn't. After all, he was hired to hack the Machine. He must have found more than just the one backdoor that Ingram installed to let the numbers out. And now that Control is on the hunt for the Machine, it may need the hacker who hacked it. Plus, who knows what the hell is going on with Samaritan over at Decima. I think we're about to find out.