Hermana, ¿pero qué has hecho?

Storyline: Sister Angela and Sister Mary park his van in front of a bank branch. They enter the bank and with the weapons hidden under their habits, commit the robbery of the century, to the astonishment of all employees and customers. After thorough police investigation the two nuns are arrested, but then appears Trini, twin sister of one of them and now all is not so clear. Were the nuns who committed the robbery?