Bridwell, Gill and Sparling change things up a bit in Secret Six 3 (Aug/Sept 68).
The story opens with Carlo, Lili, King, August and Crimson each getting a full page re-introduction, in which they survive a murder attempt. Then Tiger Force is the target, but winds up getting kidnapped.
So instead of Mockingbird sending the group out on a mission, it's the Secret Six themselves who track the former boxer. He has been taken south of the border, to a private jail run by the mob he testified against, who intend to have him executed in vengeance. Carlo goes in disguise and gets tossed into the prison as well. There they free Tiger Force, and Lili creates a mask of his face, putting it onto one of the mob guys, who they knock out.
So the next morning when the bad guys believe they are executing Tiger Force, they are really killing their own man.
The boxer explains to the rest of the group in detail how the mob got back onto his trail after the first case of the Secret Six, and how the murder attempts on the other members of the team were decoys, just meant to lure Tiger Force into the open, where they could capture him. This makes King Savage wonder if Tiger Force might really be Mockingbird, something he had dismissed, not thinking the boxer was smart enough.