Movie where teacher is trapped in student basement

Neighbors Kyu-tae and Gi-jae can't seem to escape one another - they discover they have a mutual acquaintance in Min-ah, and they even end up living together.

A recently cheated on married woman falls for a younger man who has moved in next door, but their torrid affair soon takes a dangerous turn.

Fourteen-year–old Megan and her best friend Amy spend a lot of time on the internet, posting videos of themselves and chatting with guys online. One night Megan chats with a guy named Josh who convinces her to meet him for a date. The next day, Megan is missing—forever. Based on actual cases of child abduction.