Music teacher Mi-Ju is suddenly experiencing strange occurrences seemingly related to a car accident ten years before which killed friend/cellist rival. A mysterious audio cassette turns up with a recording made of the dead girl's musical performance, a disgruntled former student threatens her life, harassing text messages suggest that her current happiness will be short-lived, and her autistic daughter has started maturing biologically prematurely and the silent girl is mysteriously drawn to a cello in an antique shop window (I wonder who it belonged to). CELLO's basic plot is another variation on one of Asian horror's master plots; that of the revelation that our traumatized/amnesiac protagonist was not such a nice person before the accident/trauma tied to a death/disappearance which is now expressing itself supernaturally by picking off the protagonist's friends, family, and human enemies. The script is hopelessly muddled with subplots involving the disgruntled former student (who didn't get into a prestigious music school because of the bad grade Mi-ju gave her), a creepy maid who comes to work in Mi-Ju's family household (a woman of no words and disquieting stares) and Mi-Ju's victim-to-be sister-in-law planning her wedding (the maid doesn't look too pleased), and the usual phone calls and text messages which do not show up on call records. Although the cinematography and music are quite atmospheric, the film's attempts to balance all these elements and more means that the pacing is erratic and just as the film starts to weave its spell we cut to another aspect of the story and watch it build up to something intriguing before once again before cutting away again. Director Woo-cheol Lee is most successful in wringing some very palpable tension from the scenes of Mi-Ju trying to teach her daughter to play the cello but cannot otherwise get us to care about the protagonist's family of potential victims (and we all know that there's a CGI-augmented long-haired ghost girl lurking in the shadows).