Alex is very close to his elderly grandmother partly because his busy parents seem to have little or no time for him. One day he surprises two boys from his school leaving her house and is shocked to find her tied up inside - they have robbed her! Alex is sworn to secrecy as his gran is worried that her daughter will think her incompetent. This secret leads Alex into trouble as the two boys accost him in the street and bully him into becoming a "bagsnatcher" (tasjesdief) for them, mugging old ladies. Alex learns how to deal with this situation in the end.