Duncan Moore returns to duty and is upset when McNally refuses to ride with him or listen to his apologies. Nick volunteers to partner with Duncan.
A car bomber seems to be targeting an Irish mobster with two separate bombs. Andy tracks down the bomber as the disgruntled tenant Theodore McDonald from Moving Day. McDonald's son was killed in a bombing exactly four years earlier.
When Duncan fields a tip, he goes out alone and ends up being abducted by the bomber and handcuffed inside a car with a bomb underneath. With the bomb squad too far out, Nick sends Andy out of the garage and tries to disarm the bomb with the help of the bomb squad over the phone. Thankfully he is successful.
Sam's ex-girlfriend Marlo Cruz later arrives at the scene. She's now with the Intelligence Division and is working the case along with Sam and Andy.