Sarah finds herself in the middle of a hostage situation at a medical testing lab. When the team realizes there's no way inside without aggravating the gunman, Charlie sends Rex in to monitor the situation.
After a reviled restaurateur's food truck explodes, killing one of his employees, Charlie and Rex find themselves with a few too many suspects. A flirtation has Charlie torn between a possible new love and Rex's reaction.
When a body is found in a shopping container, Charlie teams up with a female cop from his past to solve the crime, Rex is not a fan and keeps getting between the two, keeping the path clear for Charlie and Sarah.
On the trail of a serial arsonist, Charlie is hospitalized after a bombing breaks his leg. Unable to let the case rest, bedridden Charlie works the case, hoping to identify him before he strikes again.