[{_id:5,events:[{start:5,end:10},{start:15,end:20},{start:21,end:26},]},{_id:6,events:[{start:3,end:10},{start:15,end:22},{start:23,end:26},]},]

db.collection.aggregate([{$match:{"_id":5,},},{$unwind:"$events"},{$match:{"events.start":{$gte:15},"events.end":{$lte:250}}}])