Ksenia Sobchak is young, wealthy and famous. Her father helped bring down the Soviet Union. Now she's challenging ex-KGB officer Vladimir Putin for the Russian presidency. A perfect pedigree Perhaps. But some say she's a fake candidate, running a no-hope race to boost the Kremlin's democratic credentials. Gabriel Gatehouse travels to Russia to unravel a tale of family loyalties, a death in suspicious circumstances, and double dealings in the quest for power.