Frozen II (2019) sets out to answer the biggest mystery of Frozen – where did that choral music from the first film actually come from?

A sequel so long-awaited that one of the characters even breaks the fourth wall to note the audience looks a little bit older, “Frozen II” goes back to beyond the beginning of the first movie to deliver a complex wraparound follow-up to 2013’s breezy take on “The Snow Queen”.

With Anna, Olaf, Kristoff and Sven living happily ever after, Elsa still feels uneasy in the kingdom of Arandelle, an unease made worse by a siren song from the north that only she can hear. But when Elsa accidentally awakens the elemental spirits who dwelt beyond a magical barrier beyond the north mountain and Arandelle is forced to evacuate, Anna and Elsa must use a bedtime story told to them by their mother and father as a guide to unravel the mysteries of the past and save the kingdom.

Not since “Back To The Future II” has a sequel’s plot been so intertwined with the first film, as we flashback to way beyond Elsa and Anna’s childhood, to the time of her grandfather and a diplomatic expedition north into the lands of the Northuldra, and follow a saga of two peoples and two sisters who are destined to right a great wrong. Where the original “Frozen” had a simple story to tell, “Frozen II” has much darker ambition and sets out to tell a much more complex story – although it still keeps itself to a relatively trim 100 minute run time, resulting in some vagueness where certainty might have been more satisfying and sacrificing coherence for brevity.

Where the first movie was content to wax lyrical about the healing power of love, the sequel sets out to explore more esoteric themes such as the evils of colonialism and the damaging effects of walls and segregation on a land, its people and the environment. The animation is, of course, polished to an exquisite shine and while the songs may initially feel like a letdown from the first movie’s conveyer belt of ruthlessly sing-a-longable earworms, there’s no denying the big Broadway energy of the movie’s songs.

There’s plenty here for “Frozen” fans to enjoy and even a few sly metatextual nods to the worldwide cultural legacy overkill of the first movie but you don’t really need to have seen the first one to enjoy this – especially as Olaf helpfully recaps the first movie à la C-3PO in “Return Of The Jedi”. Taken together, both movies provide a surprisingly deep and eminently satisfying epic take on Hans Christian Andersen’s The Snow Queen, albeit one with decidedly modern sensibilities.