The goal of this event is to do a run of jewelry store break-ins (smash) and try to steal the most valuable thing possible (grab). Each progressive store will have better rewards, but an increased chance of being busted.
You will choose a card, but one of them will have an alarm which will bust the you and end your run. If you are busted, you will lose all rewards gained up to that point. You can avoid this fate by choosing to Exit With Rewards and claiming all rewards up to that point.
Every few stores there won't be any alarms and all prize cards will have increased rewards. These stores will be blue and have special blue cards.
Please note that Smash and Grab is scheduled on a rotation, so there may be days where you will not trigger the game even if you would ordinarily qualify. This is normal, and the schedule differs between players.