Agent Costas is a Secret Service agent and an enforcer for Allison Shaw in her coup to overthrow the US government.
Events of The Last Ship[]
Costas is seen outside of President Jeffrey Michener's hotel room and initially refuses to let Kara Green. Only after Kara gives him a direct order does he finally relent and they find Jeffrey dead from an apparent suicide. (“In the Dark”)
When President Howard Oliver calls his Secret Service agents to have Shaw escorted out, agents Costas and Murphy arrive and Shaw reveals she had them reassigned to Oliver's security detail against his will as Shaw forces Oliver to comply with her demands. (“Paradise”)
Costas stands to agent Raife's right at a press conference, guarding President Oliver, where he announces signing an executive order rollbacking all of Michener's domestic policies. Costas continues to guard Oliver as Shaw arrives in his office and forces him to sign an arrest warrant for Tom Chandler. (“Scuttle”)
In a flashback it is revealed that he and his partner assassinated President Michener and staged the scene to look like a suicide on Shaw's orders. (“Legacy”)
Agent Costas escorts Roberta Price and Shaw back to the White House and guards them as they try to use their centralized weapons systems to sink the Nathan James. When agent Powell finds Chandler's kids, Costas shoots Price on Shaw's orders and removed her body before returning to Shaw and Colonel Witt as they try to sink the Nathan James. During an assault on the White House, Shaw orders Costas to call in back up and take care of them personally. Agent Costas manages to surprise and shoot Sasha before being gunned down by Kara, only to reveal the bullet hit Sasha's vest and wasn't hurt. (“Don't Look Back”)