This experimental study explores how communication influences efficiency, trust and trustworthiness in a small group when one member is left out of communication. To study this problem, we introduce a novel three-player trust game where player 1 can send any portion of his endowment to player 2. The amount sent gets tripled. Player 2 decides how much to send to player 3. The amount is again tripled, and player 3 then decides the allocation among the three players. The baseline treatment with no communication shows that on average players 1 and 2 send significant amounts and player 3 reciprocates even though all players are randomly regrouped every period. When we add communication between players 2 and 3, the amounts sent and returned between these two increase. The interesting finding is that there are external effects of communication: player 1 who is outside communication sends 60% more and receives 140% more than in the no communication treatment. As a result, social welfare and efficiency increase from 48% to 73%.