I. To compare the rates of complete remission (CR) plus CR with incomplete recovery (CRi) achieved with cytosine arabinoside (ara-C) (cytarabine) plus the checkpoint kinase 1 (CHK1) inhibitor MK-8776 (Chk1 inhibitor SCH 900776) vs. ara-C alone for adults (ages 18-75) with relapsed acute myelogenous leukemia (AML).