*I do not take credit for this solution, This was posted on Playstation trophies org. I added the link below as Citation. There was no author listed on the site to credit for this solution. The youtube video was created by Wozamil, http://www.ps4trophiesgaming.com/
Edit: i believe the author to be dcollins22http://www.playstationtrophies.org/game/puppeteer/trophy/691...
"This trophy is unlocked in Act I, Curtain II. You will need to set the 22 puppet children free by pressing on their hidden locations throughout the level. During the first half of the level they are hidden behind walls, usually in groups of three. Once you reach the rooftop area they are harder to locate, and are usually found on their own rather then in groups. It's worth noting that you are allowed to lose your head/ die. You don't have to recollect the puppets during your playthrough. Furthermore, as the trophy description suggests, you need to set all puppet children free in a single playthrough, not over multiple attempts.
See the below video by Wozamil for their exact locations in the level-"