Soaking

Clara and Brighten, two siblings from a conservative rural family, sneak away after dinner to discuss a sensitive matter. Brighten confides in Clara about her struggle to maintain chastity with her boyfriend Elijah. They reveal a controversial solution called soaking, where the couple can engage in penetrative sex without moving to uphold their abstinence vow.
The twist is that a third person, in this case Clara, is needed to facilitate the act to avoid breaking the rules. Overwhelmed and conflicted, Clara reluctantly agrees to assist them in this sexual arrangement, hoping she won't regret her decision.