#1 Heroes of Olympus: The Mark of Athena by Rick Riordan
(Technically we started in 2021, but we didn't finish until 2022, the only drawback of these awesome books being the kids' bedtime read alouds.)
Percy, Annabeth, Leo, Hazel, Frank, Piper, and Jason meet in New Rome after their separate adventures in the previous two books. And it looks like their groups - Greek and Roman (who usually don't get along) - are getting along in the Roman camp just fine. Until an unplanned and unwanted (but very much forced) attack happens. Percy and his new/old friends flee the camp and head to "the ancient lands" (the real Rome) to look for an artifact that might just bring peace to their warring camps. Because, as the Prophecy of Seven states, both Greeks and Romans will need to fight side by side in order to vanish Gaea and her minions to save the entire world. But only Annabeth, daughter of Athena, can follow the mark which will lead her on a separate quest to find the sacred object. A quest that will lead her straight into the lair of her mother's oldest enemy.
I am totally loving these books. Yes, they're for young adults, but Rick Riordan is so masterful in his craft that he is keeping both my husband and I entertained just as much as our 8-year-old daughters. And while the "old enemy" was not in the least bit surprising for a mythology junkie like myself, the interaction between "her Ladyship" and Annabeth was engaging and well done. And the cliff hanger ending had all four of us scrambling to start the next book!
