2. Footprints of Change - Tong Yao's late husband believed to be a KMT member but actually an undercover CCP member, it just being found out after second arc almost ended, but her new beau had long guessed it since a friend of him and the late husband once told him that they were so similar in frugality, taste (like author and painter), and temperament.
Is vertical drama okay?
3? Hunting Love - ML took over the identity of a mafia leader's son but actually was an undercover agent, everyone just find out about it after a DNA test result that came out sometimes after ML was presumed dead (but he's not actually dead thankfully). This Ma Xiao Yu is specialized in mafia/bad guy that's actually an undercover police.