Joseph Baresh had an unbelievably good memory, able to reproduce a page from a telephone book after only glancing at it.
It's hinted that Baresh was an alcoholic, and dramatic tension is sometimes built on the question of whether his drinking would prevent him from doing his job.
Baresh volunteered for what was essentially a suicide mission. When Briggs decided to go back for him it surprised Armitage, Carter, and Collier. He was successfully rescued, and in the process brought with him a complete list of all of Soska's agents.
Baresh: All this water, you know, I'm not so sure my system can stand the shock.
[reached for a bottle of alcohol]