Shamrock was Stringer Bell's second in command while Avon Barksdale was in prison and oversaw the technical aspects of the drug operation on his behalf. Stringer sounds out his loyalty by having him followed on a trip to Philadelphia to collect a package of drugs, along with Bodie Broadus. The package is not delivered correctly, but Shamrock and Bodie keep to Stringer's orders and meticulously documented his progress, and Stringer is satisfied with their response.
Stringer entrusts Shamrock with driving Bodie to dispose of the weapons used in a misguided territory war after a young child was killed by a stray bullet. Unfortunately Bodie drops the bag of guns onto a passing freight ship instead of into the water. Little comes of it because Bodie had wiped the weapons clean of prints.
Stringer entrusts Shamrock with the set-up of CO Dwight Tilghman to allow Avon to exchange information about Tilghman with the prison authorities for an early parole hearing. Stringer, Shamrock and Country follow Tilghman and learn that he smuggles heroin from Butchie into the prison. Stringer has Shamrock deliver a package of tainted narcotics to Tilghman through Butchie, causing several deaths in the prison. Shamrock also plants narcotics in Tilghman's car to make sure Avon could successfully inform on Tilghman.
Shamrock oversees Stringer's organizational meetings at the funeral home and tries to keep to Robert's Rules of Order. He tries to keep minutes at the first meeting of the New Day Co-Op, a group of major Baltimore drug players; Stringer curtly reminds him that he is taking notes on a criminal conspiracy.
Stringer uses Shamrock to insulate himself from the street; Shamrock takes phone calls on Stringer's behalf, then organizes face to face meetings at secure locations. Stringer put Shamrock in charge of overseeing Bernard in obtaining disposable cell phones used by the organization. Stringer insisted that Bernard buy a maximum of two phones from any one outlet. Once Shamrock takes over, he stops checking up on Bernard and Bernard begins to buy phones in bulk from Lester Freamon, an undercover officer in the Major Case unit investigating Stringer. Freamon is thereby able to supply the Barksdale's crew with pre-wiretapped phones.
When Avon is paroled, Shamrock continues in his role as Stringer's assistant controlling their drug dealing through the lieutenants and crew chiefs. He is peripherally involved in Avon's turf war with Marlo Stanfield, passing messages back and forth to soldiers. Shamrock is arrested alongside Avon at the end of season three.
|Season 2 appearances|
|"Ebb Tide" *||"Collateral Damage"||"Hot Shots"||"Hard Cases"||"Undertow"|
|"All Prologue"||"Backwash" *||"Duck and Cover"||"Stray Rounds" *||"Storm Warnings" *|
|"Bad Dreams"||"Port in a Storm" *|
|Season 3 appearances|
|"Time after Time"||"All Due Respect"||"Dead Soldiers"||"Amsterdam"||"Straight and True"|
|"Homecoming"||"Back Burners"||"Moral Midgetry"||"Slapstick"||"Reformation"|
|"Middle Ground" *||"Mission Accomplished"|