WE NEED to talk about “Grandpa.”

“Grandpa” is the third episode of the new, 30-minute HBO version of High Maintenance, the terrific web series that details the exploits of the Guy (Ben Sinclair), a weed deliveryman in Brooklyn. Actually, that’s not quite right—High Maintenance is about the various people the Guy crosses paths with, from his customers to their neighbors. The Guy flits in and out of each story, but is rarely the central character.

Even within the show’s parameters, however, “Grandpa” is unique: Most of the new HBO episodes paste two shorter stories together to make a half-hour, usually with some bit of ingenious connective tissue. “Grandpa,” on the other hand, follows a single story from start to finish, and it’s not about the people at the periphery of the Guy’s delivery route—it’s about an enormous, shaggy, wolfhound-labradoodle-ish wriggle of fur named Gatsby. Sinclair and his High Maintenance co-creator, Katja Blichfeld, have made a 30-minute film about a dog that’s told almost entirely from the dog’s point of view, and it’s heartbreaking and hilarious and brilliant.

Moving High Maintenance from web to TV could have been disastrous, but thankfully, Sinclair and Blichfeld have refined what made the web series so great. The show is frequently hysterical, but it’s not exactly a comedy; it’s got an indelible New York flavor, but it isn’t too insular or self-referential; it uses pot as a plot device, not as a crutch for lazy characterizations.

High Maintenance is forever going to be referred to as “that show about the weed guy.” And it is that. But there’s plenty to love here, whether you partake or not. Sinclair and Blichfeld have made something that’s about the furthest thing from a “stoner” show as you can get: a study of relationships and modern American life and the things that make us human. Or, in Gatsby’s case, a dog.