>>> author dennis lehane is best known for his books " mystic river " and "gone baby gone." now he's working on a mystery closer to home, trying to find his dog. he's offering a novel reward for her return. mark potter has details.
>> reporter: in and around boston, searchers are putting up posters and scouring the streets hoping to find tessa , a 4-year-old beagle, who sprayed from her home christmas eve .
>> thank you very much.
>> reporter: her anxious owner is famous novelist dennis lehane .
>> she's one of those dogs. she walked into our lives and took over. just unequivocally sweet, sweet dog.
>> reporter: lehane 's books, read worldwide, have been turned into movies. " mystic river ," "shutter island," and "gone baby gone." in announcing tessa 's disappearance on his facebook page and asking for help, he made an unusual offer to whomever finds his beloved pet. he wrote, "naming of character in the next book for anyone who gets her back to us. no, really."
>> it would never just be a walk-on part. somebody who returned the dog and wanted their name in the book, i would give them lines, have them do something. i can't say here oregon villain but they would be noticeable.
>> reporter: that offer has drawn lots of attention.
>> i hope i find the dog. fame, my 15 minutes as it were.
>> anything to get your dog back. if that does it, good for him.
>> reporter: lehane 's current work, a screen adaptation of his short story " animal rescue ," has become a bitter irony.
>> i'm in the midst of writing the script every morning about a guy and his relationship with his dog that he found. this stray dog . and then while i'm out looking for my own stray dog .
>> reporter: lehane said tessa escaped through an unlocked gate and took off not wearing her collar. she was last seen in this parking lot .
>> i think she got picked up. i think she either found somebody's house or she met somebody here who took her in.
>> reporter: lehane says he is humbled by the outpouring of public support for a family pet that needs to come home. for "today," mark potter , nbc news.