The Isle of the Sirens

It's after the war with Gaea. Percy and Annabeth are finally able to get back to their relationship, the Romans and Greeks are at peace, Leo has finally fulfilled his oath to Calypso, Jason is keeping his promise to Kymopoleia while keeping a balanced relationship with Piper, Hazel is helping Frank to adjust to the newfound responsibility of being co-praetor in the Roman Legion, Nico has come out and is dating Will Solace. Everything is perfect. Right? Nope, wrong things start to change when a few months after the war, twin girls wash up on the beach at camp half-blood. A few weeks later Will goes missing, Annabeth gets seriously injured then everything unravels as an unexpected foe emerges. Will they complete this quest or will this be their last battle?