The Book of Disquiet.

Chun and Jane are siblings. They were very close as children, but after Jane graduated and started working, while Chun stayed at school for his PhD and spent most of his time in the dorm, they gradually drifted apart. One morning, Jane receives news that her brother has committed suicide. While handling his affairs, she discovers that he had already bought insurance, suggesting he had planned this for some time. To find out the reason behind his death, Jane uses his computer and starts messaging his friends on social media, slowly rediscovering the brother she once knew. In the end, Jane realizes that her search for answers was not only for her brother—and the culprit was never just one person.