Up The River by Samantha (Sam) Ruskin

Alexandra Stoner has waited five long years to get her shot at Mickey Lawton, the crime lord who murdered her identical twin sister, and she is not the woman the killer remembers. No, Deputy Marshal Alex Stoner has not been sitting idle.

When the U.S. Marshals get called in to protect an eye witness in a politically sensitive murder case, Alex is assigned to lead the team. A well-executed ambush kills two of her team the first day, leaving only Deputy Stoner to save the witness, and finally put Mickey Lawton behind bars.

Alex needs to keep her witness alive for the next three days, but the situation is complicated when her late sister's best friend shows up at Alex's mountain hideaway and refuses to leave. Alex needs to maintain her cool resolve as the stakes become more personal than ever. Will the secret her sister took to her grave finally be revealed?

One thing is certain: before it's all over, someone is going to be Up The River.