The Street of Knives - V. A. Richardson

Adam and Jade are approaching seventeen. Both have lost fathers and both have found themselves shouldering huge responsibility. Adam is running Quadrant Shipping and Trading Company, while Jade has successfully taken on her father's moneylending business. They have shown themselves capable and bright, but when it comes to working together, their pride takes over, tempers flare and neither will budge. Then Adam is approached with a lucrative but shadowy proposition. Their relationship in tatters, he chooses not to tell Jade and brings them both into terrible danger.