The Tower 2 opens with Lizzie returning to Farlow station. Her boss and former lover, DI Kieran Shaw, partners her with Arif Johar. Their first call is to a domestic violence complaint against Mark Brannon, who is accused of beating up his girlfriend, Georgina Teel and terrorising their young daughter Skye. 

The antagonistic relationship between the experienced Sarah Collins and the novice cop Lizzie Adama is at the heart of The Tower 2, as they are forced to work together for the first time and begin to get a sense of each other's unique strengths.