Inclusion Criteria:

          -  Histologically confirmed diagnosis of locally advanced and/or metastatic solid tumors,
             which are not amenable to standard therapy

          -  Part I: histologically confirmed diagnosis of advanced/metastatic small and large
             bowel carcinomas (small bowel and CRC), CPI-experienced non-small cell lung cancer
             (NSCLC) and head and neck squamous cell carcinoma (HNSCC)

          -  Part II: CPI-experienced NSCLC patients must have experienced documented disease
             progression on or after PD-L1 or PD-1 inhibitor therapy (investigational or approved):
             screening tumor assessment should confirm prior progression

          -  Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1

          -  Life expectancy greater than or equal to (>/=) 16 weeks

          -  Adequate hematologic and end organ function

          -  Measurable disease per RECIST Version 1.1

          -  Ability to comply with the protocol requirements

          -  Female participants of childbearing potential must have a negative pregnancy test
             (urine/serum) within seven days prior to the first study drug administration

          -  For women of childbearing potential: agreement to remain abstinent (refrain from
             heterosexual intercourse) or use contraceptive methods that result in a failure rate
             of less than (<) 1% per year during the treatment period and for at least 5 months
             after the last dose of study treatment

          -  For men: agreement to remain abstinent (refrain from heterosexual intercourse) or use
             contraceptive measures, and agreement to refrain from donating sperm during the
             treatment period and for at least 28 days after the last dose of study treatment

        Exclusion Criteria:

          -  If one of the following laboratory results obtained within 14 days prior to the first
             study treatment (Cycle 1 Day 1) are: soluble interleukin 2 receptor (sCD25) greater
             than (>) 2 × upper limit of normal (ULN); Serum ferritin >1000 nanograms per
             milliliter (ng/mL)

          -  Any approved anti-cancer therapy that includes chemotherapy, hormonal therapy, or
             radiotherapy within 2 weeks prior to the first dose of study treatment; the following
             is, however, allowed: Palliative radiotherapy for bone metastases less than or equal
             to (</=) 2 weeks prior to Cycle 1 Day 1

          -  Adverse events from prior anti-cancer therapy that have not resolved to Grade </= 1
             except for any grade alopecia and </= Grade 2 peripheral neuropathy

          -  Bisphosphonate therapy for symptomatic hypercalcemia. Use of bisphosphonate therapy
             for other reasons (example: bone metastasis or osteoporosis) is allowed

          -  Uncontrolled pleural effusion, pericardial effusion, or ascites that require recurrent
             drainage procedures (one monthly or more frequently). Participants with indwelling
             catheters are allowed

          -  Known clinically significant liver disease which includes active viral, alcoholic, or
             other hepatitis, cirrhosis, fatty liver, and inherited liver disease

          -  History (within the previous year) of congestive heart failure, stroke, arrhythmia, or
             myocardial infarction

          -  History of peripheral venous thrombosis or thromboembolic event (within 12 months
             prior to Cycle 1 Day 1)

          -  Significant cardio- or cerebrovascular disease within 6 months prior to Cycle 1 Day 1

          -  Known hereditary or acquired coagulopathies

          -  Clinically meaningful proteinuria

          -  Requiring dialysis (peritoneal or hemodialysis)

          -  Known primary central nervous system (CNS) malignancy or symptomatic or untreated CNS
             metastases: participants with asymptomatic-treated CNS metastases may be enrolled
             after consultation with the Medical Monitor, provided they meet the following
             criteria:

               1. Radiographic demonstration of improvement upon completion of CNS-directed therapy
                  and no evidence of interim progression between the completion of CNS-directed
                  therapy and the screening radiographic study

               2. No stereotactic radiation or whole-brain radiation within 28 days prior to Cycle
                  1 Day 1

          -  Pregnancy, lactation, or breastfeeding

          -  Allergy or hypersensitivity to components of the RO7009789 formulation or to
             components of atezolizumab formulation

          -  History of autoimmune diseases (participants with a history of autoimmune
             hypothyroidism on a stable dose of thyroid replacement hormone may be eligible;
             participants with controlled Type 1 diabetes mellitus on a stable insulin regimen may
             be eligible for this study)

          -  History of idiopathic pulmonary fibrosis, pneumonitis (excluding infectious
             disease-induced), organizing pneumonia, or evidence of active pneumonitis

          -  History of radiation pneumonitis in the radiation field (fibrosis) is permitted

          -  Participants with human immunodeficiency virus (HIV) infection, active hepatitis B
             (chronic or acute), or hepatitis C infection

          -  Active tuberculosis

          -  Severe infections within 4 weeks prior to Cycle 1 Day 1

          -  Signs or symptoms of infection within 2 weeks prior to Cycle 1 Day 1

          -  Received oral or IV antibiotics within 2 weeks prior to Cycle 1 Day 1

          -  Major surgical procedure within 28 days prior to Cycle 1 Day 1 or anticipation of need
             for a major surgical procedure during the course of the study

          -  Administration of a live, attenuated vaccine within 4 weeks before Cycle 1 Day 1 or
             anticipation that such a live attenuated vaccine will be required during the study

          -  Malignancies other than disease under study within 3 years prior to Cycle 1 Day 1 with
             the exception of those with a negligible risk of metastasis or death and with expected
             curative outcome

          -  Previous treatment with any other compound that targets cluster of differentiation 40
             (CD40) (like Chi Lob 7/4 and ADC1013)

          -  Treatment with systemic immunostimulatory agents (including but not limited to
             interferon (IFN)-alpha, Interleukin-2 (IL-2) within 4 weeks or 5 times the half-life
             of the drug, whichever is shorter, prior to Cycle 1 Day 1

          -  Treatment with investigational agent within 4 weeks prior to Cycle 1 Day 1 (or within
             5 times the half-life of the investigational product, whichever is longer)

          -  Concomitant treatment with anticoagulants (example: coumadin, heparin) except low dose
             molecular weight heparin for prophylactic purposes and direct factor Xa inhibitors

          -  Treatment with systemic immunosuppressive medications (including but not limited to
             prednisone, cyclophosphamide, azathioprine, methotrexate, thalidomide, and anti-tumor
             necrosis factor (TNF) agent within 2 weeks prior to Cycle 1 Day 1

               1. Participants who have received acute, low-dose, systemic immunosuppressant
                  medications (example: a one-time dose of dexamethasone for nausea) may be
                  enrolled in the study after discussion with and approval by the Medical Monitor

               2. The use of corticosteroids as premedication in case of dye allergy previous to
                  computed tomography (CT) scan is allowed

          -  History of severe allergic, anaphylactic, or other hypersensitivity reactions to
             chimeric or humanized antibodies or fusion proteins

          -  Participants with prior allogeneic bone marrow transplantation or prior solid organ
             transplantation

          -  Any other diseases, metabolic dysfunction, physical examination finding, or clinical
             laboratory finding giving reasonable suspicion of a disease or condition that
             contraindicates the use of an investigational drug or that may affect the
             interpretation of the results or render the participants at high risk from treatment
             complications