John and Carlos are pulled into a supernatural recreation of a Vietnam-esque jungle.
Meg Donnelly (Mary), Drake Rodger (John), JoJo Fleites (Carlos), Nida Khurshid (Latika), and Bianca Kajlich (Millie). "The Winchesters" Masters of War (TV Episode 2022) - IMDb
A secondary plot involves Mary Campbell working through her grief over the loss of her cousin, Maggie, aided by Latika.