Ian Mercer was the right hand man of Lord Cutler Beckett, and worked for him in the East India Trading Company. Beckett had Mercer do his "Dirty Work". In Dead Man's Chest, he arrives at Port Royal with Beckett and hands him the death warrants of Elizabeth Swann, Will Turner and Admiral Norrington. He later assassinates a captain at the port after he found him with a letter explaining Governor Weatherby Swann's plan to have his daughter escape to England. Mercer takes a voyage to Tortuga, hoping to capture any and all of those responsible for the escape of Jack Sparrow. There Mercer sees Elizabeth and James Norrington. Mercer returns to Port Royal to give Beckett the news. Mercer has his men capture Governor Weatherby Swann and bring him to Beckett. Beckett informs the Governor that they saw his daughter go aboard the Black Pearl, and that he was going to send his strongest fleet to crush the Black Pearl and everyone on board. Beckett tells the Governor that he will spare his daughter if he gives him his position as Governor, his influence in England, and his eternal loyalty to the East India Trading Company. The Governor agrees, and Beckett sets the Governor free. Later his crew picks up James Norrington from Isle Cruces, holding his release papers and the heart of Davy Jones. In At World's End, he journeys to Singapore to spy on Sao Feng. There Mercer discovers that the Pirate Lords will be meeting. While aboard the HMS Interceptor, Governor Swann starts asking questions about the heart of Davy Jones. To prevent him from discovering too much, the Governor is killed, presumably by either Beckett or Mercer. After the Black Pearl crew are turned into Beckett by Sao Feng, he informs Feng that Beckett is going to keep the Pearl, being the only ship that can out run the Flying Dutchman. Sao Feng creates a diversion, allowing the Pearl to escape Beckett, with Mercer finding himself in a duel with Hector Barbossa. Mercer is ordered by Beckett to go aboard the Dutchman to tell Jones to follow Sao Feng. While aboard, Admiral Norrington is killed by Bootstrap Bill Turner. Mercer then has his men place cannons on either side of Davy Jones' chest, and takes the key to the Dead Man's Chest, taking the Dutchman under his command. Mercer remains on the Dutchman during Calypso's Maelstrom. During the battle of Calypso's Maelstrom, a cannon ball nearly hits Mercer, but Davy Jones moves him out of the way, saving his life. Davy Jones looks down and sees that all of the East India Trading Company's soldiers around him are either dead or wounded. Jones takes the opportunity to get back his key. He grabs Mercer and smothers his nose and mouth with his tentacles, suffocating him. Jones then takes the key from Mercer's dead body.