Ruby asks for the heroes' help to look for Dorothy in "Once Upon a Time" season 5 episode 18.

"Once Upon a Time" season 5 episode 18 is entitled "Ruby Slippers." According to Spoilers Guide, Ruby pursues her search for Dorothy and she enlists her friends' help in finding the latter.

As per flashbacks, Ruby and Mulan were seen in Oz, where they met Dorothy. The trio also saw Zelena's return to Oz, which leads them to find a way to finally take her down. In the middle of things, Dorothy mysteriously vanishes, which prompts Ruby to look for her.

During Ruby's search for her friend, she finds herself in the Underworld, where she is set to reunite with the others. She is going to work hand in hand with Snow, Regina, and Emma as they try to search for Dorothy.

In addition to Ruby's search for Dorothy, "Once Upon a Time" season 5 episode 18 also sees a struggle involving Snow and David, as they are not able to deal with their son Neal. They plot a strategy centering on the escape of one of them from the Underworld.

Previously in episode 17, Belle saw Gaston in the Underworld, where she had to decide on something that posed a threat to Rumplestiltskin. Entitled "Her Handsome Hero," episode 17 saw Belle turn to the wish granter in order to save her child from Hades, Spoilers Guide reports.

"Once Upon a Time" season 5 episode 17, "Her Handsome Hero," aired on April 10, while episode 18, "Ruby Slipper," just aired on April 17.