This contribution foicuses on a neglected problem in the current sociology of trust, namely actors' calculated attempts to gain the advantages of trust through fraudulent means. The purpose is to illustrate the potentials and limitations of such tactical trust investments by studying the ways in which secret agents attempted to infiltrate the resistance movement during the German occupation of Norway (1940 - 1945). Drawing on the archives of the Norwegian resistance movement, this study shows how infiltrators, using dramaturgical methods alone, could gain access to the trust of others. This was accomplished by copying typical traits present in everyday relations of trust; that is, first, the tendency to put trust in the trust of others, and, sencond, the gradual test of the reliability of actors. It is suggested that the study of tactical investments in trust under risk conditions is of sociological interest, since the otherwise often elusive, gamelike aspects of mutual strategic action are made visable.