Ep 20. Leap of Faith

When the ponies of Equestria hear about a new "Flim Flam Miracle Curative Tonic" that can cure any ailment, they are skeptical. However, when the Flim Flam Brothers arrive in town and put on a flashy show to sell their tonic, even the most skeptical ponies start to believe. Applejack and Granny Smith remain unconvinced, but their faith is tested when Granny Smith is injured and the tonic appears to work. Applejack's brother, Big Mac, is convinced that the tonic will cure his constant aches and pains, and he convinces Applejack to invest in the Flim Flam Brothers' business.

As the ponies continue to consume the tonic, they start to experience strange side effects. Rainbow Dash's wings become weak, Pinkie Pie becomes jittery, and Twilight Sparkle starts to lose her magic. Applejack begins to lose faith in the tonic, but Big Mac remains convinced that it works.

When the Flim Flam Brothers refuse to offer a money-back guarantee, Applejack decides to investigate their tonic. She and Rainbow Dash follow the brothers to their secret manufacturing facility and discover that the tonic is a fraud. The ingredients are harmless, but the tonic itself has no curative properties.

Applejack confronts her brother and the other ponies, telling them the truth about the tonic. However, Big Mac is unwilling to believe that he has been taken advantage of, and he defends the Flim Flam Brothers. Applejack challenges her brother to a leap of faith, asking him to trust her and jump into a river.

Big Mac jumps into the river and is rescued by Applejack, who explains that she wanted to show him that sometimes the people we trust can let us down. In the end, Big Mac apologizes for his stubbornness, and the ponies of Equestria learn an important lesson about skepticism and blind faith.