A slap on the wrist is a very mild inconsequential punishment or warning, so getting away with one means that he was going to get away with a very light punishment or warning.
Context: Everything had been going alright, he was even going to get away with a very light punishment or warning, but then m's.
Hypothesis: Everything had been going alright, he was even going to get away with a slap on the wrist, but then m's.

Is the hypothesis incorrect? (Yes, no, or unknown)?