About what the code does, I added the details in the code as comments for better context, and clarity. The idea is to provide it with file name(s) and it will start going through all the .torrent files in the current directory (and 1 level under), parsing each one and checking it for the file name(s) provided.

#! /bin/bash
#
# Search .torrent file based on 'Name' field.
#
# USAGE:
# cd ~/myspace # location of .torrent files
# Run `findtor ~/list.txt` (if `findtor.sh` is placed in `~/bin` or `~/.local/bin`)

# Turn the list of file names from ~/list.txt (or any file passed as argument) into an array
readarray -t FILE_NAMES_TO_SEARCH < "$1"

# For each file name from the list...
for FILE_NAME in "${FILE_NAMES_TO_SEARCH[@]}"
do
    # In `pwd` and 1 directory-level under, look for .torrent files and search them for the file name
    find . -maxdepth 2 -name '*.torrent' -type f -exec bash -c "transmission-show \"\$1\" | awk '/^Name\: / || /^File\: /' | awk -F ': ' '\$2 ~ \"$FILE_NAME\" {getline; print}'" _ {} \; >> ~/torrents.txt
done

Let me explain what I am trying to do by e.g. so you can understand better. Let's say I have 100 .torrent files in a directory. 2 of them will download xxx.epub and yyy.epub respectively if added to a bittorrent client, but I don't know which 2 out of the 100.

So what my script does is, (1) use find to go through all .torrent files in pwd and pass each .torrent file, as it comes by, to transmission-show which will parse the .torrent file and output metadata in human readable format. We'll then use awk to get the file name the torrent file will download and run that against the list.txt which has file names we are looking for, i.e. xxx.epub and yyy.epub.

#! /bin/bash
#
# Search .torrent file based on 'Name' field.
#
# USAGE:
# cd ~/myspace # location of .torrent files
# Run `findtor ~/list.txt` (if `findtor.sh` is placed in `~/bin` or `~/.local/bin`)

# Turn the list of file names from ~/list.txt (or any file passed as argument) into an array
readarray -t FILE_NAMES_TO_SEARCH < "$1"

# For each file name from the list...
for FILE_NAME in "${FILE_NAMES_TO_SEARCH[@]}"
do
    # In `pwd` and 1 directory-level under, look for .torrent files and search them for the file name
    find . -maxdepth 2 -name '*.torrent' -type f -exec bash -c "transmission-show \"\$1\" | awk '/^Name\: / || /^File\: /' | awk -F ': ' '\$2 ~ \"$FILE_NAME\" {getline; print}'" _ {} \; >> ~/torrents.txt

    # The `transmission-show` command included in `find`, on it own, for clarity:
    # transmission-show xxx.torrent | awk '/^Name: / || /^File: /' | awk -F ': ' '$2 ~ "SEARCH STRING" {getline; print}'
done