MongoDB provides transactions at a document level, if you need to go multi-document-transaction, you're out of luck as far as I know.

The best you can do according to the docs is using the isolated operator:

Using the $isolated operator, a write operation that affect multiple documents can prevent other processes from interleaving once the write operation modifies the first document. This ensures that no client sees the changes until the write operation completes or errors out.

Isolated write operation does not provide “all-or-nothing” atomicity. That is, an error during the write operation does not roll back all its changes that preceded the error.

The $isolated operator does not work on sharded clusters.

Have a look at two-phase commits, this is probably the closest you'll get to two-document transactions: docs.mongodb.org/manual/tutorial/perform-two-phas…