The spoilers are about to start flowing, so now would be the time turn away if that matters to you.
The original Clash of the Titans, if you don’t already know, involves the goddess Thetis taking offense when Queen Cassiopeia brags that her daughter, Princess Andromeda, is even more lovely than the goddess. As the Greek gods were wont to do, Thetis takes offense and informs the people of Argos that she’s sending the Kraken – the hit-beast of the gods – to destroy Argos, a fate they can avoid by chaining Andromeda out on the beach as a sacrifice to it.
The remake takes divine petulance a step further by having the gods behave so irresponsibly that all of humanity is rebelling against them and destroying their temples – which is a problem, since the gods derive much of their power from human worship. The exception is Hades – the god of the underworld – who has learned to thrive on human fear instead. Seeing the human rebellion as an opportunity to overthrow Zeus, he manipulates the situation for his own benefit. When the insolent people of Argos proclaim the beauty of Andromeda, he announces – in Zeus’s name – that she must be sacrificed to the Kraken or the city will be destroyed. In so doing, he expects the human lack of respect to turn into full-blown hatred (which will deprive Zeus of power) and outright terror (which will increase his own power).
With the plot thus set, the sequence of events of the two movies begins to converge. Perseus goes on a quest to behead the gorgon Medusa so he can use her petrifying gaze to defeat the Kraken. Motives and details vary (and I won’t go into them at length), but the gist is much the same. The main difference is in the muddled message of the remake.
The original didn’t really have a message; it was just a wacky adventure to slay a monster. The sequel tries to introduce a theme revolving around human independence and immortal accountability, which is potentially interesting if you’re following the religion-versus-secularism conflict in modern culture, but the movie can’t seem to make up its mind whether to follow through on that plot and have Perseus succeed purely on his mortal merits or go through a “character arc” in which Perseus learns to accept his godly heritage. In the end, he doesn’t really do either, which makes me wonder why the writers introduced this personal conflict in the first place.
As for the butchering of mythology, the actual myth of Perseus goes something like this:
- Danae, the mother of Perseus, was the daughter of King Acrisius, not his wife. Acrisius had them sent out to sea to die in an effort to avoid a prophecy that his grandson would eventually kill him (that never works, by the way). Both Perseus and Danae survived the sea journey to end up in Seriphus.
- Seriphus had its own problems, as the king there – Polydectes – had his lecherous eye on Danae. Perseus was a master c*@#-blocker, though, so Polydectes tricked Perseus into promising to kill Medusa, which he figured would be a sure way to get the youth killed.
- Seeing his son in a trap, Zeus took steps to make sure Perseus had the means to accomplish the quest. He arranged for him to have a sword and shield (with a mirror-polished inside surface), a pair of winged sandals, a helmet that turned him invisible (provided by Hades, incidentally – see below), and a bag suitable for toting around a severed monster head.
- Guided by the advice of the Graeae (the oracles with only one eye among the three of them), Perseus found Medusa’s lair and ambushed her in her sleep (sorry, no epic battle, folks).
- On his way home he happened to see Andromeda chained to the rocks as a sacrifice to the Kraken. The offense that got her there, incidentally, was being reckoned more beautiful than the Nereids, vain sea nymphs who complained to Poseidon when the word got round. Perseus – after extracting a promise from Andromeda's father that he could marry her – intervened to save her. That’s right: the Kraken was just a target of opportunity, not the object of Perseus’s quest.
- Hades was somber, not evil, and he actually liked ruling the underworld. As I recall, he chose the underworld as his domain (he, Zeus, and Poseidon drew lots to see who would get first choice).
- Drops of Medusa’s blood spilled by Perseus during his post-beheading travels caused poisonous snakes to develop in various parts of the world. Not exactly giant scorpions, but far worse raping of mythology occurs in these movies.
- Pegasus belongs in the story of Bellerophon, not the story of Perseus.
- There is no story from Greek mythology that involves “jinn” in any way whatsoever.