Flirt-A-Tosis is the 43rd episode Season 7.
The Hub Map send Princess Twilight Sparkle to Equestria to help Princess Celestia who is infected by some strange virus that has made her too flirtatious and soon the virus starts to spread all over Equestria and only Twilight and her friends need to find the cure before all of Hub Island is affected.
The episode starts in the Friendship Rainbow Kingdom Castle where in the throne room, Twilight was reading her books while Spike and his friends are just playing outside when Twilight's magic gem on her bracelet begins to glow which means indicating that she is being called by the Hub Map.
As she taps on it with her hoof, Lief's face appears on the hologram telling her to come to his castle right away, it's an emergency!
After Twilight flies to Lief's castle, she entered the throne room and Lief presses the crystal button that summons the map, showing that it's calling Twilight to Equestria. After a train ride on the Hub Express, Twilight arrives at the train station only to find a worried looking Princess Luna who takes her to the Canterlot castle by teleporting them there, where they find Princess Celestia and Discord in the throne room, acting strange.