From subway . . . _ Monday night. Wednesday morning. Friday lunchtime._ Holland Bakker plans her journeys to work around the times the handsome Irish musician, Calvin McLoughlin, plays his guitar in the 50th Street subway station. Lacking the nerve to actually talk to the gorgeous stranger, Holland is destined to admire him from a distance. Then a near-tragedy causes her busker to come to her rescue, only to disappear when the police start asking questions. ** To Broadway . . . ** Keen to repay Calvin, Holland gets him an audition with her uncle, Broadway's hottest musical director. When he aces the tryout, Calvin's luck seems to have turned - until his reason for