Matthew Gray Gubler is all smiles while filming this Reid-centric episode.
Enjoy these behind-the-scenes photos from the filming of the episode...
Watch Criminal Minds on Wednesdays at 9/8c on CBS and CBS All Access.
When a bizarre hieroglyph found under a deceased homeless man's armpit is the same from previous casualties a few years ago, the BAU is called in to investigate. Also, Reid decides to take his mother out of a clinical study early to bring her home with him, in "Surface Tension."