The inventor of a breathalyzer that detects cancer is found dead. Sherlock determines that he was in fact murdered and it likely had to do with a recent claim by a pseudonymous tipster that the inventor's research was falsified. Sherlock and Joan discover that the research was true and that the tip was false. When the wife of Hank Prince - the CEO of the company that owns the patent to Granger's research - is murdered, Joan and Sherlock conclude that Hank posed as the tipster and killed Granger to temporarily decrease the potential value of his company so he would owe less to his wife in their divorce settlement. Meanwhile, Bell is approved to reenter the field and asks for help to track down a young witness who is afraid to testify against a powerful drug dealer. The old man who was protecting the young witness kills the drug dealer and gets killed in the process.