The secrets of the legendary lost continent of Atlantis will start to be unfold when both Marinette and Adrien coincidently go spend their holydays in Lisbon, where Shadow Moth is after one powerful relic that may give him the power to get their Miraculous. With the help of a new friend, will the heroes defeat the villain and prevent the city from being sank?

It's time for a lake trip for the Heeler boys, with this being Thomas' first time. But when Stripe and Rad start to compete with each other over who is Thomas' favourite uncle, they may ruin their nephew's first lake trip... and possibly their relationship.