Commando Raid (III) - S1.E15

The children mount a night raid on the castle to find Garcia, as they are convinced that he is in the dungeons. They find Garcia (but not Poopsnagle, as they do not realise that he is also in the dungeons), however Sator traps them in the tidal cell, where the tide will eventually drown them. Matt, however, has been following their movements and he is able to help the children escape from a high air grate.