The dragons unidentified mate

Dragons are the most powerful clan, which is ruling the world with an iron fist. All the other clams are considered beneath them. Humans are considered the lowest of the low.
Drake Hamilton is the most powerful orange dragon. He is rich, handsome and powerful. Dragons have the option to choose their mate. But once they sleep with anyone, automatically that person will become their mate. They cannot change it. Only the death of their mate will give them the chance to choose another one.
Using that as an advantage Drake's step sister drugs him, so that she can sleep with him and become his mate. But fate has another thing planned.
Drake escapes and sleeps with a human named Nyra.
Nyra has a hidden past. When she tries to help an injured Drake, under the influence of the drug, Drake forces himself on her.
Marking them as mates. Nyra now has an orange Dragon Tattoo, which is marked as Drake's mate. she is adamant to hide it and Drake is desperate to find her.
Who will succeed in their quest?
Will he find his mate?
What happens when her past comes back to threaten her? will he save her?