Thank you for your help. Applying the formula worked - but it wasn't so easy to define a dynamic link that also works when the location and filename of the workbook changes.
=HYPERLINK(MID(CELL("filename",A1),FIND("[",CELL("filename",A1)),(FIND("]",CELL("filename",A1))+1)-FIND("[",CELL("filename",A1))) & "'Sheets2'!B1","Details")
Cheers,
Michael