Who is Lyra Tonks?

Harry gets a Floo call from Andromeda: she's adopted a little girl, Lyra, but can't reveal Lyra's birth parents. It's clear her parents are Death Eaters, but who? Then, Draco wants to become reacquainted with his aunt and cousins, but why? And now, the Ministry is forcing Harry to work with Draco in order to solve a string of poisonings. How does this all relate? Eventual Drarry.