Please don't list this on a work's page as a trope. Examples can go on the work's YMMV tab.
Tear Jerker: Citizen X
An in-universe example: the film starts with a child's body being discovered. Forensic scientist Burakov examines the body and determines that the child has been murdered. On learning that the apathetic cops haven't bothered to search the scene, he orders them to do so. Cut to some hours later: one by one, the cops bring about a dozen child-sized body-bags into the morgue. Burakov examines them all and by the end, he's crying even while he's talking emotionlessly into the tape recorder.
Burakov's quiet break down near the end, caused, after years of having to fight and struggle to get scraps of support from his own government, by finding out that the detectives in the FBI's serial crimes division consider him to be an outright iron-willed badass hero, and finding out that after years of deprivation, he was finally going to get the support he's needed to solve the case.