S4·E10 Clean Sweep (2)

Jarod and Rachel Burke discover that the two dirty Secret Service agents, who are their most direct link to the killers of a fellow agent, are found slain, forcing them to begin their investigation all over again. However, while romantic sparks fly between the pair, Jarod suddenly disappears and is tortured by the murderer, who is on a crazed mission to eliminate everyone he thinks is involved in the agency's corruption. The crossover starts on The Pretender S04E10 Spin Doctor (I).