In Dirty Laundry, Neon, a lonely late-shift laundromat attendant, meets Night, a murder mystery novelist who saves her from the rampage of other customers and sweeps her off her feet. Neon falls in love with Night overnight, which brings her to his apartment where she discovers a briefcase containing one million baht. Overcome by greed, she takes the briefcase home with her and hides it at the laundromat. After Night finds out, he comes to reclaim the briefcase from Neon who gladly gives it back only to find that the briefcase is missing. The only way to identify the thief is through the log of customers who came to the laundromat. The suspects include Judo, a good-looking college student; Chompoo, Night's apartment caretaker; Momay, a sexy karaoke girl; and Nick and Smile, a rock couple. All have suspicious behavior. Who is the real culprit and how will the love story between Night and Neon turn out?