FULL EPISODE SYNOPSIS
It's the eve of St. Patrick's Day. Detective Mac Taylor is picking up a sandwich from his favourite deli. It's very crowded, as usual. He meets a beautiful woman, but they cannot talk for long, as he receives a message that calls him to a crime scene.
Two dead men have been found in a warehouse. One of them can be identified as Michael Paley, the other one is unknown. Stella finds traces of pure gold on the floor, while Danny finds a four leave clover. The team takes photos and samples from the crime scene. It turns out that Michael Paley is a investigative journalist, together with his partner Cam Vandemann. The team suspects the second victim to be Vandemann and that one of their investigations has led to their murder. Sid does the autopsie and does a computer reconstruction of the unidentified victim's face, that has been severely damaged. Sid learns that the victim is not Vandemann. In the victim's blood he finds with several vaccines, pointing to him having travelled internationally recently. Sid also found some impressions on his scalp, possibly from the murder weapon, that he has to investigate further.
Danny and Lindsey find out that there was a fourth man at the crime scene who must have picked up and pocketed the gun that had been dropped by the murderer. On one of the victim's clothes Lindsey finds residue of a green algae while Danny discovers that the clover is indiginous to Ireland.
Mac meets with Reed. Reed is a friend of Vandemann and asks Mac to come and meet the scared man. Mac agrees reluctantly.
When Mac returns to the deli a while later, a letter from the woman is waiting for him there, thanking him for the kindness he has shown her.
Hawkes identifies the intentions on the unknown victim's head injury as the identifcation number of a gold bar, worth half a million dollars. Because of its identification number they can trace it's location. Hawkes and Stella get access to the gold storage room and start looking for that particular gold bar, helped by Adam.
Meanwhile, Lindsey has found out that the algae she found is used by one bar in Manhattan to brew green organic beer. She and Danny head out there and question the bartender, Finnegan Hansard. Finnegan is able to identify the unknown victim from the photo they show him as Charlie Cooper. He had been a customer and someone Finnegan had a grudge against, because he had sold him a fake engagement ring that caused his girl to break up with him and Charlie then slept with her. Finnegan says he has no idea why Cooper might have talked to two journalists, but that he liked to hear himself talk and make a fast buck.
Stella checked Cooper's travel records and learned that he has been to China recently, which explains the vaccines in his body. He had been working for Elemental Precious Metals (EPM), a company that makes money with reclaimed gold and incidently also shipped the gold bar that was used as the murder weapon.
Mac spots a newspaper with the same add for an open house he noticed the woman in the deli had circled. He decides to take a chance and leaves her a message with the agent there, asking her out for diner. She likes it.
Later, Mac questions the head of EPM, Thom Weir, about Charlie Cooper, his company and the gold. Mac doesn't trust the man and neither does Flack, they both suspect he is involved in the murder.
At night, Mac meets with Vendemann. Vendemann tells him about his investigating of international gold fraud and that the killer was a cop. When Flack hears this, he tells Mac that it surely wasn't a cop. He thinks it was someone in a uniform that Vandemann mistook for a cop.
Mac tests the gold bar. It is made out of a cheap metal called tungsten and only gold plaited. The clover and some other traces found at the crime scene lead to a memorial in Central Park, where they arrest Vandemann. The team investigates the murder weapon. Mac manages to make the registration number visible again. To everyone's surprise the gun belongs to Finnegan Hansard, the bartender.
The St. Patrick's Day Parade is marching, when Flack arrives at the pub. Finnegan, spotting him, jumps over the bar and starts running. Flack follows in hot pursuit. The men barge through the parade. Danny trails behind, calling backup over his phone. Finnegan then runs into a dead end, where Flack arrests him. Flack interrogates him, while Mac and Stella question Thom Weir again. They are certain that he hired Finnegan to kill the journalitst and gave him a security guard uniform to do the job. Only that Vandemann wasn't there yet. Finnegan says he won't go down for this alone. Weir thinks he can get away with it, if he remains silent, but then the treasury agent comes in and brings up a slew of charges against him. He realises that he won't get away after all.
Mac goes on his date with the beautiful woman, her name is Aubrey Hunter.