Database
[{_id:"Parent1",kids:[{_id:"Test1",grandkids:[{name:"Blah"}]}]},{_id:"Parent2",kids:[{_id:"Test1",grandkids:[{name:"Bloh"}]}]},{_id:"Parent3",kids:[{_id:"Test2",grandkids:[{name:"Bloh"}]}]},{_id:"Parent4",kids:[{_id:"Test1",grandkids:[{name:"Blaaaaaah"}]},{_id:"Test7777777777",grandkids:[{name:"Bloh"}]}]}]
Query
db.collection.find({"kids._id":"Test1","kids.grandkids.name":"Bloh"})