One Last Dance is the penultimate episode of the original run of Mt. Ararat. The title is a reference to the senior prom, which is shown in a montage at the end of the episode.
Unlike most of the post-reboot episodes, One Last Dance focuses on only one plotline: the MOTH event in Portland. The Creative Writing class gathers outside the Topsham Starbucks, before carpooling down to Portland, where they get pizza at Slab and finally get to the MOTH event.
The episode ends with a montage depicting both the senior prom and Mullen's return to Maine.