Writer: Marc Norman
Dir.: John Llewellyn Moxey

Jim Phelps: Peter Graves
Paris: Leonard Nimoy
Dana Lambert: Lesley (Ann) Warren
Barney Collier: Greg Morris
Willy Armitage: Peter Lupus

Dr. Jerome Carlin: Christopher Connelly
Dr. M. Vazan: Robert Ellenstein
Colonel Leo Orlov: Larry Linville

While working for the IMF in a chemical plant, Interoco, Barney gets caught. The IMF is forced to take an outsider in their midst who is unaware of whom he's working for. Though he is dying, Barney is questioned by security chief Orlow and by the scientist who is responsible for the chemicals, Dr. Vazan. 

All operation needs to involve the Interco computer and there is only one other man who is able to work with it: Dr. Jerry Carlin. Jerry does not respond to Dana's offer, but has to work for the IMF when agents Paris and Doug discover heroin in Jerry's girlfriend purse. They arrest her and promise Jerry to let her go if he cooperates by retrieving the vital information for the IMF. 

Paris wonders whether it is right to involve a civilian person by force. Jim justifies the action by all the people who already have died and will if Interoco goes on as it does now. The time Dana interviews Dr. Vazan the IMF and Jerry penetrate the building via tunnels. With Dana's help Paris takes over as Dr. Vazan. 

After Dr. Vazan has interrogated Barney and left a tiny speaker in Barney's ear Barney makes confessions implicating all who need to be implicated in the IMF's plan. They are replaced – by Jim and Jerry. Soon afterwards Barney is declared dead by the doctor and taken to the autopsy room into Doug's hands. Thanks to Jerry the chemicals and the formula are destroyed. Orlov always stays alert and is informed by one security guard that a stranger is amongst the guards – too late, the IMF, Jerry and the real dr. Vazan, who is taken along, have just left.