Elementary - P versus NP

Bouncing back, this was a good balance between Watson's character development and Holmes' detective prowess. It feels like the shows is taking a turn for the technical, chasing rogue developers and the masterminds behind them.

Mark Schäfer /CBS ©2013 CBS Broadcasting, Inc. All Rights Reserved

Elementary "Solve for X" (S02E02): Watson is remembering a deceased patient's birthday at the cemetary and ends up going for coffee with his son, Joey, while Holmes invites himself to a crime scene with two shooting victims. Holmes smells phosphors on the victim's walls. A black light reveals 'maths' written on the walls and ceiling.

Watson returns to the Brownstone after Joey pitches her to be an investor in his bar to find a topless mathematician working on the equations Holmes found at the crime scene. He identifies the equations as the 'P versus NP' problem, which the victim and a partner were weeks from solving. Watson and Holmes are referred to another professor, and they recognize the victim's partner's handwriting in a journal. But, Detective Bell calls to report another dead body, the same person Holmes and Watson discovered.

Watson asks Holmes for a $5,000 advance on her salary for Joey's bar, but Holmes wants to make sure she's not being taken advantage of, especially after she reveals she's given Joey money before. Bell finds a bug at the second mathematician's apartment and Holmes discovers a camera across the street wireless transmitting a video feed. They trace the signal back to a private security firm who was spying on the mathematicians because they wanted an exclusive on the solution. The security firm had the equations checked by a different professor to determine how far along they were, and she told them it was bogus. Turns out, it was the same professor who identified victim number two to Holmes and Watson, but she has an alibi for the murder.

Doing situps in front of pictures of mathmaticians at 2am, Holmes gives Watson not $5,000 but $20,000 to 'buy her way of out the guilt' for killing Joey's father, as 'guilt' is the worst kind of poison in his opinion. Holmes goes back to visit Tanya Barrett (the professor who misled the security company) to ask about anyone who might want to frame her. She points him at her ex-boyfriend, but he denies sending incriminating emails found in his email account.

The second shooting victim is awake, and identifies Tanya as the person who shot him. Holmes and Watson look at the security footage again that Tanya used for her alibi. Watson spotted cheap drinks and determined it was happy hour, and someone faked the timestamp. They return to Tanya's partner and discover she found the solution to P versus NP and killed the others to buy time until she could use it to steal loads of cash. She also used the software developed from the solution by her partner to hack the videotape time, as well as her ex's email account.

Watson decides to give Joey a scholarship and not a bar investment, which he is not thrilled about. Holmes claims he wants to accompany Watson to the cemetery next time...