The lavender smells sweet tonight

The lavender smells sweet tonight. Albus has been given a code by Harry, it's urgent. He needs to relay this to Neville. Time is running out. Owls are being intercepted. Draco is missing. Scorpius is tormented by nightmares of endless searches, of werewolves and death. But what does it all mean? And how does Albus know it's all related?