Star wakes up from dreaming about flying in the clouds and eating Goblin Dogs to discover her bed littered with Goblin Dog wrappers. Marco suspects that she snuck out to the Goblin Dog truck during the night, but Star has no memory of going their. A receipt she spits out proves she did go to the Goblin Dog truck, probably in her sleep. The following night, Star has Marco watch her sleep and see whatever happened before happens again. Marco tries to stay up, but eventually falls asleep himself. He wakes up to see Star, in her Mewberty form, emerge from a dimensional portal with the whole Goblin Dog truck. When she returns to normal and wakes up, Marco tells her about what just happened. Hearing that she went through a portal without using Dimensional Scissors and becoming that butterfly creature when she defeated Toffee worries her. She awkwardly asks her parents about it, which leaves her feeling even more worried, especially when her father over exaggerates that it could lead to chaos. After being told that she could get locked away forever, Star decides to keep her sleep-portaling a secret until she can find a way to stop it. Star has Marco chain her to her bed and watch over her while she sleeps. He also chains himself to her, so the next time he dozes off he will be alerted the moment she makes a move.
Later that night, Marco had fallen asleep, but woke up the moment Star transformed and opened a portal. She breaks free from the chains and flies through the portal, dragging Marco along with her. Flying through the void between dimensions, Marco tries to wake up Star. He succeeds and tells Star to fly back through the open portal leading to Mewni. As she does so, her Mewberty form wears off before she reaches it, causing herself and Marco to drift aimlessly through the void. All of a sudden, Glossaryck appears through the portal with a chain of cloths wrapped around him. Star and Marco use him to return to Star's bedroom. They are revealed to have been saved by Eclipsa, who was alerted when Glossaryck wandered into her tower. Marco is shocked to find the notorious Eclipsa walking around, but Star wants to call it a night and urges him out of her bedroom.
Star tells Eclipsa about her sleep-portalling and asks if she knows how to stop it. Eclipsa, however, encourages Star to embrace these dreams and see where they lead instead of running away from them. She says it is the only way to find out what she is truly capable of, saying "All knowledge if good knowledge". So the following night, Star decides to take Eclipsa's advice and see where her dreams take her. Despite Marco's concerns, Star stands by her decision. She goes to sleep and starts to dimension-hop in her mewberty form, while Marco sits and watch with Glossaryck in his lap.
- Eden Sher as Star Butterfly
- Adam McArthur as Marco Diaz
- Esmé Bianco as Eclipsa Butterfly
- Jeffrey Tambor as Glossaryck
- Alan Tudyk as River Butterfly
- Grey DeLisle as Moon Butterfly
- Ludo makes a cameo appearance drifting through dimensional space after Star tossed him into the void in "Toffee".
Storyboards and Concept