Tickets at $1.50 and $1.00 have been placed on sale at the Co-operative Society's store for the Christmas mystery play, "Eager Heart," which will be given in Copley Hall, Boston, on Monday evening and on Tuesday and Wednesday afternoons. This play, by Miss Alice Buxton, the English authoress, has met with great success in London during the last few years. Several Harvard men are in the cast this year.