Mysterious “Mauritius” hits the stage in April. Suspenseful and engrossing, what begins as a story of two sisters at odds over how to handle their late parents’ estate develops into a plot full of twists and manipulation when it appears that the sisters have come into possession of some very valuable and unique stamps. Who wants them, and how far will they go to obtain them? Theresa Rebeck’s excellent script will have you guessing and second guessing. “Mauritius” will be directed by Karen Ruetz, and it was chosen as our MAT show for this season.