Pencil could have been a thrilling whodunit but it also wants to be a message movie that rails against private educational institutions, and in trying to be both, it fails to be a satisfying film. And to make matters worse, its premise isn't wholly original as well, for it is inspired from the Korean thriller 4th Period Mystery.

The film begins promisingly with Nithin (Shariq Hassan), the school's student and the son of a film star, being murdered by an unknown assailant. Then, it goes back by a few months and shows us the various characters who have a motive to kill the boy — Shiva (GV Prakash), the school topper who is Nithin's bete noire; Maya (Sri Divya), Shiva's crush and a bold girl who rubs him the wrong way; teachers Nandini (Suja Varunee) and Sridhar (Thirumurugan) whose compromising video is in the boy's hands; Anthony Gonsalves (VTV Ganesh), another teacher whom he disrespects; the girl who Nithin is blackmailing; the local boy whom he beats up for hitting on a classmate; and so on. Maya finds Shiva in an incriminating set-up, but decides that he is innocent and together, they decide to track down the murderer before he can leave the school's premises.

Barring the cliched and unnecessary romantic portions, Mani Nagaraj does a decent job of setting up the mystery in the first half. But the second half is a great let-down. While we expect a tense thriller, what we end up with are amateurish investigative scenes and mood-killing comedy that takes away every ounce of tension in the script. Just because the setting is a school, should the scenes be this juvenile? It is also marred by the choice of the actors who play the school's faculty. TP Gajendran plays the school's principal and his phone's ringtone is Kundrathile Kumaranukku kondattam! Should we say more?

The dialogues hitting out at private schools also feel manipulative, especially the climactic monologue, though Abhishek saves it from being a mere rant with his sincere performance. Also, with the hero's character often designated to a secondary role (even during the investigations, it is Sri Divya's Nancy Drew-ish Maya who takes the lead), it is Shariq Hassan (making his debut) who walks away with the film with an arresting performance. The film feels alive whenever he is in the scene, which is why it is a pity that his character dies midway and has to merely be a dead body. Along with him, the film also becomes lifeless.