Who vs Whom
If in doubt, reword the clause to see which personal pronoun you need: he/him, she/her, etc. Then replace that
pronoun with who or whom, using the following rule:
Use WHO for he, she, they, we:
The people who just boarded the plane are in a rock band.
(Reword: They just boarded the plane—so use who.)
This boy rescued us
(Reword: He rescued us so use who)
Use WHOM for him, her, them, us:
The cousin whom we met at the family reunion is coming to visit.
(Reword: We met him at the family reunion—so use whom.)
The agent with whom I spoke was able to help me. (Reword: I spoke with her—so use whom.)