Episode 89 of "MacGyver"
s05e06 Halloween Knights

Mac is called to Jack´s hangar, but when he comes there, Jack is gone. The only clue leads to a cemetary. Mac goes there, thinks that he sees Jack, but suddenly he´s trapped underground - by Murdoc. Murdoc asks Mac for help in locating his sister, whom he has kept secret for all years, but who´s now been kidnapped by Murdoc´s old employers: a cartel of assassins-for-hire. Mac and Murdoc attempt to sneak into the cartel´s club, using Halloween costumes and a secret meeting between the leaders of the cartel. But just as they think they have found the sister, they are caught in deadly gauntlet...