It forms a hydrazone, of course, and water leaves the scene. An NH from the NH2, hydroxide will attack. Resonance occurs and then the carbon grabs H back. Reduce the carbonyl and then the side-chain now is plain.
Hydroxide base is still present, it steals the last H plus.
Now add a little heat, the N2 leaves without a fuss. The carbon gets a hydrogen producing an alkane. Now the carbon chain is plain. Reduce the carbonyl and then the side-chain now is plain.