var orders = db.Orders
    .Join(db.Shipments,
        o => o.OrderID,
        s => s.OrderID,
        (o, s) => new { Order = o, Shipment = s })
    .Join(db.LineItems,
        s => s.Shipment.ShipmentID,
        l => l.ShipmentID,
        (s, l) => new { Order = s.Order, Shipment = s.Shipment, LineItem = l })
    .Join(db.StatusTypes,
        s => s.Shipment.StatusTypeID,
        st => st.StatusTypeID,
        (s, st) => new { Order = s.Order, Shipment = s.Shipment, LineItem = s.LineItem, Description = st.ExternalDescription })
    .Where(x => x.Order.AccountID == accountId)
    .GroupBy(x => x.Order.OrderNumber)
    .ToList()
    .Select(
        x => new OrderStatusViewModel
        {
            Date = x.Max(y => y.Order.Created),
            OrderNumber = x.Key,
            Cost = x.Sum(y => y.LineItem.UnitPrice).ToString(),
            Status = x.Max(y => y.Description)
        }
    );