Brett Dohn and Emma Blackstone are set to have the wedding of the season in Central Park, until Brett turns up dead. The CSIs discover he's been wrapped in bubble wrap and apparently wasn't killed in the room where he was found. Mac finds yellow paint transfer on a curb nearby, especially puzzling as the curb was painted at 6 a.m. and Sid determined the groom died between 2 to 3 a.m. Sid makes a gruesome discovery when he unwinds the bubble wrap--someone has shoved a cell phone into the laceration that killed Brett. Hawkes discovers evidence that orthopedic pads were removed from the groom's shoes, but comes to conclude the shoes were switched out by the killer, based on the yellow paint and the shoes' worn appearance.
Hawkes and Flack find the primary murder scene--the hotel room where Brett was staying the night before, and conclude that a missing wedding gift might contain the weapon. Hawkes and Mac match hair from Brett's clothes to one of the groomsmen, George, but while George admits to wrapping Brett in bubble wrap and moving the body to satisfy a hundred thousand dollar bet that Brett would make it to the altar, as well as switching shoes with Brett, he denies killing his friend. A bit of green goop leads Danny and Flack to the caterer, Timothy Maxwell, whose child had a birthday party the day Brett was killed. Phone records from Brett's cell indicate he was calling Timothy incessantly, and Timothy admits to reaching a breaking point when he was called away from his son's birthday to change the catering menu at the last moment. He sliced into Brett with a spatula from a wedding gift, and shoved his cell phone into his body before leaving.
Stella leaves the courthouse after testifying at a preliminary hearing to make a frightening discovery: someone has left a box on her car. After the bomb squad declares it safe, she opens it to find puzzle pieces inside. After confronting Drew Bedford, who insists he didn't send her the puzzle, she brings it back to the lab. She notices blood splatter on it and sets Adam to the task of reassembling it. He does, revealing a partial 3-D architectural landscape of New York. There's one piece missing, so Stella goes to Drew's and finds a piece under his desk. She apologizes to him on the way out. Adam tells her the piece isn't a match, so she and Lindsay go to the building and the floor the piece would have depicted where they find another box, a chalk outline of a body and a satchel.
Stella is puzzled; so far she can't find a personal connection in all this to her. She and Lindsay follow up on a tiny piece of redwood found in the corner of the first box, which leads them to a store where a pedophile named John Andrews work. They question him, but his ankle bracelet provides him with an alibi.
When Mac sees the puzzle, he realizes it's connected to him, not Stella. It's a roadmap of the places in New York that are significant to him: his first apartment, his first crime scene and the building where he got engaged. A third box is discovered on the roof of that building, with more puzzle pieces and another piece of debris, this one limestone from the Alamo. Mac realizes the fragments, along with an imprint on the satchel, are connected to the Tribune Tower in Chicago, which features stones from world landmarks on it. Mac arrives in Chicago at the Tribune Tower and gets a call from the 333 stalker, asking him how it feels to be home.