Lab assistant Emma Hedges is now training to be a forensic chemist, and on the cusp of seeing her mother's murder case finally resolved. Daniel is to give evidence against his father. Will Emma and Daniel's relationship withstand the pressure? Will justice be served? Meanwhile, professors Sarah Gordon and Kathy Torrance are investigating a deadly bombing campaign. Homemade devices are going off around Dundee, with critical clues hidden inside the bombs. Will the team track down the bomber before their identity goes up in smoke?