Castor and Pollux, the Gemini twins who are now going by the names Casey and Lux, have been fleeing from the wrath of Zeus and Hades for thousands of years. Whilst still on the run, they come across James and Kate who are spending six months holidaying in Greece. When they find out that Kate is the new wife of their biggest enemy, they're unhappy and with due cause. The Gods have now found them... 
 This short story served one real purpose. To show that Kate has no idea just how archaic and strict the Gods (including Henry) are. She has a lot to learn before she takes her place on the throne of the Underworld. 
 I'm not generally a fan of novellas for books in a series. Especially if they are centred around the main characters that a series follow. Why? Because normally they come in an anthology with multiple other stories for series I'm not interested it. Also, they're often not long enough for me to really get involved with the story and the characters. Whilst this was a single story (and only $0.99!), it was a little too short for me to really get back into Kate and Henry's world. I did enjoy the pseudo-love triangle that's developing with James, Kate and Henry but in the end, consider Kate is married to Henry, I don't see that little flirtation between Kate and James going anywhere. 
 I think that you could skip this story and not miss out anything important from the series.