The spring Seo Dal-mi lost everything, Nam Do-san's letters kept her company. Fifteen years later, she needs him by her side to prove Won In-jae wrong.
To preserve Dal-mi's past and to support her future, Choi Won-deok asks Han Ji-pyeong to pull off an impossible task.
Ji-pyeong scrambles to transform Do-san into the man of Dal-mi's dreams. A rude awakening prompts In-jae to close one door and open another.
Despite differing pasts, Dal-mi and In-jae fight for their dreams at the same starting line. Ji-pyeong sets out to protect Dal-mi and help Do-san.
Dal-mi and In-jae present their teams' ideas on the hackathon stage. A story about Dal-mi's upbringing moves Ji-pyeong to fight for her success.
In-jae uses lessons from her father and stepfather to her advantage. A clash over company shares tests Dal-mi, who turns to Ji-pyeong for advice.
Grappling with his feelings for Dal-mi, Ji-pyeong avoids her. Do-san's knowledge of Won-deok's condition inspires a business idea for Samsan Tech.
Devastating news gives Dal-mi another reason to make the app a success. Won Du-jeong's plan to teach Do-san and Dal-mi a lesson backfires.