La cité engloutie

The Autobots are hard at work at installing some jet-looking devices onto the sides of Optimus Prime's trailer when Carlos comes running in, frantic about something. He mutters something about a girl, and whether or not it's time.
Apparently a hologram of a young girl has come across the screen at Autobot headquarters, requesting assistance. The Autobots ignore it because they've found a Mini-Con signal in the sea and soon take off for action, Carlos hoping that it will lead them to the girl.
Once at the bottom of the sea, Hot Shot goes off to do some recon and discovers a sunken city further below the sea. The Autobots make their way down when they're attacked by the Decepticons.
Optimus Prime has Hot Shot and Red Alert distract them while he and Smokescreen make their way to an entrance in the city. Prime's oxygen bubble around his trailer cab begins to break from Megatron's blast, and the kids begin to get flooded from inside Optimus Prime.
Optimus Prime eventually makes his way ins

Next episode

S01E12 - Le volcan