So, recently, a bunch of Kraken eggs have hatched, bringing them back form a few centuries of extinction for unknown reasons. Also, turns out that when their sea-based population gets too high, some grow themselves a hardened skin exoskeleton/armour that makes them look a lot like crabs.
Krakens are carnivorous, huge and fast. Also, their hardened skin makes them impervious to almost any guns that aren't as powerful as artillery cannons. A tank might be able to stand its ground against one that is roughly its own size, but those are the extreme low end of the size scale. Your typical kraken is somewhere between the size of a house and a mansion.
Your average kraken is also famished in spite of its photosynthetic symbiotes.
Cities, towns and villages are obvious targets for these monsters. Lots of fresh meat, all packed into a small area.
The only weakness of a kraken is its eyes, and they know it and defend them. And anyway, there isn't really anything important behind the eye. It can just use its sense of smell to hunt if you blind it.
On top of all this, in this timeline, the War to End All Wars (WWI for you lot) actually worked. There hasn't been any war in the last hundred years anywhere. Almost all military equipment has either been recycled, or was rusting away somewhere waiting for its turn.
So we don't really have anything with which to fight back against them.
The first strike lasted a week. Only one in a hundred survived. There are a thousand Krakens in Europe alone! Some have tried hiding underground. But food shortages bring them out, to see their shelter crushed by a hungry kraken who sniffed them out.
Many have moved to the polar regions, but none have returned.
An average kraken only needs to eat about one cow or human a week.
Is there any way I can survive along with my family?