  An informed sender communicates with an uninformed receiver through a
sequence of uninformed mediators; agents' utilities depend on receiver's action
and the state. For any number of mediators, the sender's optimal value is
characterized. For one mediator, the characterization has a geometric meaning
of constrained concavification of sender's utility, optimal persuasion requires
the same number of signals as without mediators, and the presence of the
mediator is never profitable for the sender. Surprisingly, the second mediator
may improve the value but optimal persuasion may require more signals.
