detective work
noun [ U ] uk/dɪˈtek.tɪv ˌwɜːk/ us/dɪˈtek.tɪv ˌwɝːk/
调查，查找，搜寻
the activity of searching for information about something, often over a long period
After a lot of detective work, I managed to find out where he was living. 经过大量的调查，我终于设法找到了他的住处。
Compare: detection