Published in Bullet #017, 06/05/1976.
"Big trouble on the hidden treasure trail." Bill Busker was one of Fireball's favorite musicians and an old friend, a one-man-band working the streets for tips. He is given a coin in his hat which Fireball discovers is an 18th century doubloon that can be opened and inside it is a note saying "Treasure here at sunset June 6th". As the two ponder this oddity, Catriona and two armed goons show up at the cafe they were at and take the coin back at gunpoint.