The episode starts off in the park at the tennis court, with Supergirl and Katana getting ready to start a Tennis tournament match against the Flash and Cyborg. Supergirl explains how excited she is about being Katana's Tennis partner for the tournament, also explaining how Kryptonians weren't very sporty. Katana then tells Supergirl to not worry, due to her Super Speed, Super Strength and mad Reflexes, while reassuring Supergirl that's all they needed to win the A.C Cup.
Cyborg then teasingly, remarks that Katana should take her last look at the trophy from over the net, with a competitive spirit. He then High-Fives the Flash and the game begins, with Katana telling Supergirl to follow her lead, as well as teasing the opposition, remarking that visiting hours are between 3 and 5, to see the AC Trophy. The game then begins with Flash taking the first serve. Katana skilfully manages to hit the tennis ball over the net to Cyborg, who hits it back at Supergirl.
Supergirl's attempt to hit the ball, causes the ball to go flying past Cyborg and Flash, going right threw a tree. Supergirl quickly apologizes to Katana, with her telling Supergirl to shake off her beginners nerves. Supergirl's second attempt to hit the ball causes the ball to crash in the middle of a road and create a colossal crater. After that Flash is seen speedily hitting the ball, while running side to side, with spectators including; Beast Boy, Cheetah and Starfire trying to keep an eye on him. Katana manages to hit the ball back to Cyborg, who extends his robotic arm to hit the ball to Supergirl, who then hits the ball so hard, it demolishes an entire building, that was about to be bulldozed.
Supergirl then hears, the cries of a distressed civilian, via her super sonic hearing and flies off the court in the middle of their match. Supergirl then see's the Double Dare Twins, who are trying to steal an old lady's purse. Supergirl flies in to help, just as the handbag is stolen and attempts to reclaim the handbag for the old lady. The Twins, then hide the handbag behind their backs and try to fool Supergirl into thinking they're only taking a walk in the park and that they purse they stole, was just lost property. The Twins then begin to cart-wheel down separate paths. Supergirl quickly reacts and realizes they are moving towards each other. She serves up the tennis ball with her racket which hits a lamppost, bouncing off and causing a crater in the middle of the tennis court, right in front of Margot, who falls in while cart-wheeling through the court. Aliki manages to save herself and taunts Supergirl. Just then Supergirl's tennis ball bounces off a statue of Superman and knocks her into the hole as well, along with the tennis net and trapping them both.
When Supergirl lands, Katana, Cyborg and Flash approach her, with Katana looking unhappy and Supergirl trying to apologize. However Katana gives Supergirl the trophy for being an amazing Super Hero.
- The title of this webisode serves as a pun to double trouble.
- This episode was listed as the ninth webisode of season 2 on YouTube.