It’s an office building with fifteen floors (mostly vacant) located in a modern office plaza. During weekdays, there is a guard on duty and the lobby is open for 24 hours.
It was built on the site of the former Northeast Tavern where, thirty years ago, Trinity bludgeoned a man to death in the bar's bathroom.
Arthur Mitchell is online in a library, looking up information and the floor plans for 100 Oceangate.
Frank Lundy has returned to Miami and is tracking The Trinity Killer. He suspects that Trinity, a repetitive killer, will return to this location to reenact a crime. As Lundy stands in a sunken plaza outside 100 Oceangate, he makes observations into a tape recorder.
Arthur is also there, scouting the building. He spots Lundy, and assumes that he's been found out. At first, Arthur tries to hide, but then he changes his tactics. He boldly walks across the plaza towards Lundy and deliberately bumps into him, dropping his keys. They make eye contact during a brief conversation as Lundy hands him back his keys.
Arthur then crosses the sunken plaza, walks up the steps to the street, where he catches bus 432. Lundy's intuition tells him there's something odd about the guy, and he adds a brief description of the stranger into his taped-recorded notes: “White male, maybe 6' 4”; 200-220 pounds, age around 60, hair gray, eyes blue... something in them.”
Arthur returns to the building, pretending to be a potential tenant. The security guard takes him on a personal tour of the place, during which he meets a sandwich shop employee. By the time Arthur leaves, he has gathered information about the building and how long it takes for the security guard to complete his rounds.
After dark, just as Lundy predicted, The Trinity Killer has returned to the site with murderous intent. Meanwhile, Dexter has obtained Lundy's recorded notes and they lead him to the building on the same night. Dexter pushes the elevator button for the twelve floor to divert the security guard who goes to investigate. However, Dexter's too late to save the victim -- the sandwich shop guy. He finds the security monitors just in time to view Trinity smashing in the man's head with a hammer.
Dexter races up the stairs to catch him, but Trinity escapes and takes off in his van. Dexter follows him to his home and discovers that he has a family.
At the crime scene, Dexter takes photos of Earl’s corpse, relieved that Trinity’s cycle of three victims is compete -- for now.
Joey Quinn is disturbed by the smell in the room. Vince Masuka says the body has been decomposing for two days because the the building was closed over the weekend, with no AC. Dexter discovers a smudge on the wall but, as he collects the evidence, Masuka grabs the bag and tells him to worry about the blood. A wound on the victim shows an oval grid pattern and that is determined to have been caused by a framing hammer.
- When Dexter listens to Lundy’s tape of his description of Trinity, it says that he’s “190-200 pounds.” This contrasts with the “200-220 pounds” that Lundy says when recording.
- Before Arthur bludgeons Earl Doorman to death, he provokes a drunk named Mike to beat him up.