Writing about Adventure Time’s fourth season last year, I described it as both “fantastic and slightly disappointing” due to its reluctance to continue to expand creatively. But if season four maintained the level of quality and creativity of its prior season, season five ups the game by embracing the show’s potential for melancholy and complexity without sacrificing its trademark absurdist entertainment.

That’s evident right from the first two episodes, which introduces an alternate reality – with Finn (voiced by Jeremy Shada) struggling to survive in an Ooo where the unexplained apocalypse never occurred – while Jake (voiced by John DiMaggio) shoots the shit with transdimensional wish granter Prismo (voiced by Kumail Nanijani). It’s both incredibly dark – and joltingly experimental – while allowing for the warm, juvenile humour that makes the series so appealing.

That careful blend of serious and silliness is expertly maintained through the remainder of the series, which goes from strength-to-strength over its fifty-some episodes. On the silly side of the ledger, one of the strongest innovations of season four – the glorious “Five Short Graybles” – is reimagined not once but twice; meanwhile in “We Fixed a Truck”, Finn and Jake do just that, titling it Hot Daniel. “A Glitch is a Glitch” and “James Baxter the Horse” bring guest animators into the fold – David O’Reilly and James Baxter – to accelerate the show’s imaginative evolution; I’m yet to see season six, but I understand there’s more of this on the way. There’s also an impressive list of guest actors, including the likes of Donald Glover, Aziz Ansari and Oscar-winner Cloris Leachman.

But the real appeal of season five to me was how effectively it embraced its darker, more mature undercurrents. Despite being a show that transfixes infants, Adventure Time’s fifth season offers a rich consideration of themes such as family, relationships – both romantic and platonic – and a remarkably nuanced take on political power. In episodes like “Rattleballs” and “James”, it becomes increasingly apparent that Princess Bubblegum (voiced by Hynden Walch) is a barely-benevolent dictator, unafraid to sacrifice individuals for the perceived good of the Candy Kingdom; simultaneously, the show hints at a relationship between Bubblegum and vampire Marceline (voiced by Olivia Olson) – one that, unfortunately, remains coded (apparently due to the sensitivity of the international market).

The show’s always been grounded in a complex consideration of family, whether it’s the legacy of Jake and Finn’s dad, the heroic Joshua, or Marceline’s combative relationship with her own father (voiced by Martin Olson, the real-life father of Marceline’s voice actor). Family is at the core of this season’s best episodes, which explore the contentious bond between Flame Princess and her father, the surrogate-father-daughter bond between Marceline and Simon/the Ice King, or Jake’s attempts to get to know his new children. These relationships range from irreparably toxic to genuinely touching, finding more truth than any number of shallow family sitcoms.

When I wrote about season four, I wrote that it was content to stay in third gear; no longer. Season five of Adventure Time well and truly moves the show into another gear, and I’m looking forward to finding out –in season six – whether or not that’s the show’s top gear. Strongly recommended.