The story of every episode of Mad Men is a self-contained puzzle box, and the title usually serves as the critical piece. Unravel the meaning behind the title and you unlock the entire narrative. Some can be more cryptic than others, though, and “The Hobo Code” took me a couple of viewings to properly crack open.

The trick behind this episode is that despite the title, the brief flashback scenes revealing the dirt-poor poverty in which Don Draper (or rather, Dick Whitman) grew up provide context for the story here, but they’re not the most revelatory scenes in the episode. Rather, the true heart of “The Hobo Code” comes in the second-to-last scene, wherein Don verbally spars with his paramour Midge’s new proto-hippie friends, who have completed their creeping intrusion into the Don/Midge affair.

Through the episodes to have come so far, we’ve seen these people at the periphery — a vague awareness that Midge wasn’t any more exclusive to Don than he’s been to her. A hint here, a comment there. Then a television showed up in Midge’s apartment, which Don jealously goaded her into tossing out the window. Then a bearded beatnik showed up at Midge’s shortly after Don came a-callin’, prompting Midge to bring both men along to a beat cafe to snark it out. Now Don arrives at her apartment only to find it’s already overrun with her countercultural buddies.

It precipitates the end of their relationship, though that ending is never stated outright. You can see it in Don’s face when she refuses to go with him on a moment’s notice to Paris, though. Midge still retains the cunning, impish light in her eyes that clearly draws Don to her, but it’s clouded now by pot smoke — and more to the point, Don doesn’t want to have to share Midge with anyone, sexually or otherwise. Midge clearly has fallen for her scruffy leftist pal Roy, to the point that Don remarks on it. It’s his concession of defeat, punctuated by tucking a check worth about $18,000 in present-day dollars into her halter top before walking out the door.

The check, incidentally, came as an out-of-the-blue bonus from Don’s real boss, Burt Cooper, who hides his keen wit behind a façade of eccentricity. This scene, too, is quite revelatory; Cooper praises Don for being “totally self-interested” like himself, encouraging the younger man to run out and buy a copy of Atlas Shrugged. Don has no idea who Ayn Rand is, but he’s clearly put off by Burt’s stark characterization. Even though it clearly was intended in a flattering way, Don seems stung by it.

But Burt isn’t wrong. And therein lies the crux of “The Hobo Code”: Don Draper goes to great pains to be private, to hide his feelings and his past as an impoverished, unwanted child of a prostitute from the world, yet the persona he projects isn’t necessarily the one he intends to. And there’s some truth to how other people describe Don. As Burt says, he is self-interested. And as Midge’s beatniks rightly point out, he does trade in lies — not only the ones he presents at his job as an ad man, which they deride, but also in who he is. Their comments are contrasted with Don’s memories of his father filching on a promise to a wandering transient, a miserly tendency which earned the Whitman household a permanent symbol in “hobo code”: An old, weather-worn mark meaning “a dishonest man lives here” had been etched permanently into a fence post at the edge of the Whitman property, with the family none the wiser.

Rattled by the hippies’ accusations and his memories, Don clearly doesn’t want to be labeled and known by others for traits he despises. A jolt of conscience seizes him, and he heads home to wake his son Bobby, solemnly promising never to lie to the boy. And yet, the next day he unthinkingly follows his daily routine, closing behind him the office door with “his” name bolted to it, continuing the masquerade that he is Don Draper, not Dick Whitman. In his life, he’s become both the hobo and his father: Leaving behind a life that made him miserable, but becoming a liar in the process.

Which brings us back to that scene in Midge’s apartment, as the beatniks snipe at Don for selling lies, provoking him to speak with genuine contempt for the first time in the show — not the simmering disdain he occasionally directs at Pete Campbell, but true venom.

“There is no big lie,” he tells them. “There is no system. The universe is indifferent.” He mocks them for adopting the look and demeanor of vagrants but lacking the motive force that drove the drifter who once visited his family’s farmstead only to be treated with contempt in return for his manners and his sincere desire to earn his keep. He was a man who left behind everything for a life free of obligations, willing to do what it took to get by day-to-day; Midge’s friends, by contrast, are simply acting out. They don’t know true hardship, and while they proclaim the evils of modern society they do so from the comfort of a spacious apartment paid for by Midge’s freelance work for advertising and greeting cards. They’re as fraudulent in their own way as Don. There may be no big lie, as Don says, but the world is build on countless small ones.

We see Don’s untruths reflected in the relationship between Campbell and Peggy Olson; he treats her with a sort of condescending contempt, but he’s willing to offer just enough empty praise to get into her pants again when it suits his purposes. And we see it in Salvatore Romano’s closeted homosexuality, the lascivious skirt-chasing he pretends to indulge in as a way to mask his real desires. But when confronted with the truth, sometimes the lie is preferable. A client propositions Sal, who realizes he’s not ready to act on his true nature. And Peggy ultimately sees the truth of Campbell’s feelings for her: A surly, ugly jealousy, a childish resentment at knowing Peggy takes pleasure in something besides him. He’s incapable of sharing even a moment’s happiness that her first copywriting assignment was a success. Totally self-interested.

Yet the lies work, as Don demonstrates by walking out the door of Midge’s apartment and casually strolling past a pair of policemen who would have given Midge and her crew grief. Dressed in his disguise of respectability and commitment, Don can go anywhere and do anything, like the vagrant he met as a child. Midge, on the other hand, is tied down by her connection to her “free” friends who emulate the lifestyle of hobos without truly understanding the underlying ethos that once drove men to ride the rail. Again, Don has become both the vagrant and his father: Liberated from the shackles of his former life and free to go where he choses by falsely adopting the guise of a respectable man.