I thought this was back on par with books 1 & 2.

I really like Cassandra and Apollo who both care for one another but don't do anything about it because he's the boss and she is the employee.
But a house party at a new individual's place in Olympus puts them pretending to be in a relationship to figure out what is really going on (per Zeus instructions) and what danger is in their city.

Their dynamic together is fire