Inclusion Criteria:

          -  Patients must have completely resected (as per standard of care) melanoma of cutaneous
             origin in order to be eligible for this study; patients must be classified as stage
             IIB or IIC cutaneous melanoma using the American Joint Committee on Cancer eighth
             edition; patients with melanoma of mucosal or other non-cutaneous origin are not
             eligible; patients with melanoma of ocular origin are not eligible

          -  Patients must have a negative sentinel lymph node biopsy or undergo a failed attempt
             at sentinel lymph node biopsy including lymphoscintography which fails to show a
             sentinel lymph node from the melanoma primary site

          -  Patients must have systemic cross-sectional imaging (positron emission tomography
             [PET]/computed tomography [CT] or CT of chest, abdomen, and pelvis) which shows no
             evidence of metastatic disease

          -  Patient must be able to comprehend and sign a written informed consent and be willing
             to comply with all study procedures

          -  Patients must have an Eastern Cooperative Oncology Group (ECOG) performance status of
             0 or 1

          -  Absolute neutrophil count (ANC) >= 1,500 microliter (mcL)

          -  Platelets >= 100,000/mcL

          -  Hemoglobin >= 10 g/dL

          -  Total bilirubin =< 1.5 x institutional upper limit of normal (IULN) (except Gilbert's
             syndrome, who must have a total bilirubin < 3.0 mg/dL)

          -  Serum glutamic-oxaloacetic transaminase (SGOT) (aspartate aminotransferase [AST]) and
             serum glutamate pyruvate transaminase (SGPT) (alanine aminotransferase [ALT]) and
             alkaline phosphatase =< 2 x institutional upper limit of normal (IULN)

          -  Serum creatinine =< 1.5xULN OR measured or calculated creatinine clearance >= 60
             mL/min

          -  Patients known to be human immunodeficiency virus (HIV) positive are eligible if they
             meet the following criteria within 30 days prior to registration: stable and adequate
             CD4 counts (>= 350 mm^3), and serum HIV viral load of < 25,000 IU/ml; patients may be
             on or off anti-viral therapy so long as they meet the CD4 count criteria

          -  Women of childbearing potential must have a negative urine or serum pregnancy test
             within 28 days prior to registration; women/men of reproductive potential must have
             agreed to use an effective contraceptive method for the course of the study through
             120 days after the last dose of study medication; should a woman become pregnant or
             suspect she is pregnant while she or her partner is participating in this study, she
             should inform her treating physician immediately; a woman is considered to be of
             "reproductive potential" if she has had menses at any time in the preceding 12
             consecutive months; in addition to routine contraceptive methods, "effective
             contraception" also includes heterosexual celibacy and surgery intended to prevent
             pregnancy (or with a side-effect of pregnancy prevention) defined as a hysterectomy,
             bilateral oophorectomy, or bilateral tubal ligation; however, if at any point a
             previously celibate patient chooses to become heterosexually active during the time
             period for use of contraceptive measures outlined in the protocol, he/she is
             responsible for beginning contraceptive measures; patients must not be pregnant or
             nursing

          -  Therapy must be initiated within 120 days of surgical resection of the sentinel lymph
             nodes and within 6 months of initial diagnosis.

          -  Patients must be willing to have archived tumor specimens utilized for correlative
             studies if available

          -  Patients must not have known active hepatitis B virus (HBV) or hepatitis C virus (HCV)
             infection prior to registration

        Exclusion Criteria:

          -  No other prior malignancy is allowed except for the following: adequately treated
             basal cell or squamous cell skin cancer, in situ cervical cancer, lobular carcinoma of
             the breast in situ, atypical melanocytic hyperplasia or melanoma in situ, adequately
             treated stage I or II cancer (including multiple primary melanomas) from which the
             patient is currently in complete remission, or any other cancer from which the patient
             has been disease free for three years

          -  Current immunosuppressive therapy including > 10 mg/day of prednisone within 14 days
             of enrollment is not permitted; inhaled or topical steroids, and adrenal replacement
             steroid doses =< 10 mg daily prednisone equivalent, are permitted in the absence of
             active autoimmune disease

          -  Patients must not have active autoimmune disease that has required systemic treatment
             in past 2 years (i.e., with use of disease modifying agents, corticosteroids or
             immunosuppressive drugs); replacement therapy (e.g., thyroxine, insulin, or
             physiologic corticosteroid replacement therapy for adrenal or pituitary insufficiency,
             etc.) is not considered a form of systemic treatment

          -  Patients must not have a history of (non-infectious) pneumonitis that required
             steroids or current pneumonitis

          -  Patients must not have received live vaccines within 42 days prior to registration;
             examples of live vaccines include, but are not limited to, the following: measles,
             mumps, rubella, chicken pox, shingles, yellow fever, rabies, Bacillus Calmette-Guerin
             (BCG), and typhoid (oral) vaccine; seasonal influenza vaccines for injection are
             generally killed virus vaccines and are allowed; however, intranasal influenza
             vaccines (e.g., Flu-Mist) are live attenuated vaccines, and are not allowed

          -  Patients must not have a history or current evidence of any condition, therapy or
             laboratory abnormality that might confound the trial results, interfere with the
             patient's participation for the full duration of the trial, or indicate that
             participation in the trial is not in the patient's best interests, in the opinion of
             the treating investigator

          -  Patients must not be pregnant or lactating

          -  Prior therapy with anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CD137, or anti-CTLA-4
             antibody (or any other antibody or drug specifically targeting T-cell co-stimulation
             or checkpoint pathways) is not permitted

          -  Treatment with any investigational agent within 14 days of first administration of
             study treatment is not permitted