Solving a murder is like putting together a giant jigsaw puzzle. Sometimes, the pieces snap into place with ease and other times, they don't fit. The police must meticulously reconstruct the puzzle. Once all the pieces are found, investigators must then figure out how everything fits together, crack the case and bring justice for the victim.

Journalist Susan Zalkind investigates the triple murder that took her friend’s life, the national tragedy that shook her city, and the haunting question that connects the two events: if the murders had been solved, could the Boston Marathon bombing could have been prevented?

Cold Squad is a Canadian police procedural television series first broadcast in 1998 that followed the investigations of a part of the Vancouver Police Department Homicide Division tasked with solving cold cases, the titular Cold Squad, as led by Sergeant Ali McCormick. The cast of Cold Squad was diverse and changing, McCormick being the only character to appear in all 7 seasons. Some notable series regulars include Detective Tony Logozzo in seasons 1-2, Sgt. Frank Coscarella in seasons 3-4, Sgt. Len Harper in seasons 5-7, Insp. Vince Schneider season 1, Insp. Simon Ross season 2, Insp. Andrew Pawlachuk seasons 3-7, Det. Mickey Kollander seasons 3-6, Det. Nicco Sevallis seasons 3-6, Christine Wren seasons 4-7, as well as Det. Samantha Walters and Const. Ray Chase in season 7. Between the second and third seasons, almost the entire on-screen cast other than Julie Stewart were replaced. This along with the new sets, a significant revamp of the credits and theme music, and even having McCormick's hair change from auburn to dirty-blonde all contributed to a considerable reworking of the series.

When her husband, Lee, is murdered, Sarah Manning comes to realize that she knows nothing about his past. Sarah begins to question who Lee actually was and what he did in his work for a powerful global organization. And why did Lee, a salesman, need to carry a gun?